Sunday 21 July 2013

HTML Introduction HTML Introduction HTML Introduction HTML Introduction

     <<<<HTML Introduction>>>>

Example

<html>
<body>

<h1>My First Heading</h1>

<p>My first paragraph.</p>

</body>
</html>



What is HTML?

HTML is a language for describing web pages.
  • HTML stands for Hyper Text Markup Language
  • HTML is not a programming language, it is a markup language
  • A markup language is a set of markup tags
  • HTML uses markup tags to describe web pages

HTML Tags

HTML markup tags are usually called HTML tags
  • HTML tags are keywords surrounded by angle brackets like <html>
  • HTML tags normally come in pairs like <b> and </b>
  • The first tag in a pair is the start tag, the second tag is the end tag
  • Start and end tags are also called opening tags and closing tags

HTML Documents = Web Pages

  • HTML documents describe web pages
  • HTML documents contain HTML tags and plain text
  • HTML documents are also called web pages
The purpose of a web browser (like Internet Explorer or Firefox) is to read HTML documents and display them as web pages. The browser does not display the HTML tags, but uses the tags to interpret the content of the page:
<html>
<body>

<h1>My First Heading</h1>

<p>My first paragraph.</p>

</body>
</html>

What You Need

You don't need any tools to learn HTML at W3Schools.
  • You don't need an HTML editor
  • You don't need a web server
  • You don't need a web site

Editing HTML

HTML can be written and edited using many different editors like Dreamweaver and Visual Studio.
However, in this tutorial we use a plain text editor (like Notepad) to edit HTML. We believe using a plain text editor is the best way to learn HTML.

Create Your Own Test Web

If you just want to learn HTML, skip the rest of this chapter.
If you want to create a test page on your own computer, just copy the 3 files below to your desktop.
(Right click on each link, and select "save target as" or "save link as")
After you have copied the files, you can double-click on the file called "mainpage.htm" and see your first web site in action.

Use Your Test Web For Learning

We suggest you experiment with everything you learn at W3Schools by editing your web files with a text editor (like Notepad).
Note: If your test web contains HTML markup tags you have not learned, don't panic. You will learn all about it in the next chapters.

.HTM or .HTML File Extension?

When you save an HTML file, you can use either the .htm or the .html file extension. There is no difference, it is entirely up to you.

HTML Headings

HTML headings are defined with the <h1> to <h6> tags.

Example

<h1>This is a heading</h1>
<h2>This is a heading</h2>
<h3>This is a heading</h3>




HTML Paragraphs

HTML paragraphs are defined with the <p> tag.

Example

<p>This is a paragraph.</p>
<p>This is another paragraph.</p>




HTML Links

HTML links are defined with the <a> tag.

Example

<a href="http://www.w3schools.com">This is a link</a>


Note: The link address is specified in the href attribute.
(You will learn about attributes in a later chapter of this tutorial).

HTML Images

HTML images are defined with the <img> tag.

Example

<img src="w3schools.jpg" width="104" height="142" />

HTML Elements

An HTML element is everything from the start tag to the end tag:
Start tag *
Element content
End tag *
<p>
This is a paragraph
</p>
<a href="default.htm" >
This is a link
</a>
<br />


* The start tag is often called the opening tag. The end tag is often called the closing tag.

HTML Element Syntax

  • An HTML element starts with a start tag / opening tag
  • An HTML element ends with an end tag / closing tag
  • The element content is everything between the start and the end tag
  • Some HTML elements have empty content
  • Empty elements are closed in the start tag
  • Most HTML elements can have attributes
Tip: You will learn about attributes in the next chapter of this tutorial.

Nested HTML Elements

Most HTML elements can be nested (can contain other HTML elements).
HTML documents consist of nested HTML elements.

HTML Document Example

<html>

<body>
<p>This is my first paragraph.</p>
</body>

</html>
The example above contains 3 HTML elements.

HTML Example Explained

The <p> element:
<p>This is my first paragraph.</p>
The <p> element defines a paragraph in the HTML document.
The element has a start tag <p> and an end tag </p>.
The element content is: This is my first paragraph.
The <body> element:
<body>
<p>This is my first paragraph.</p>
</body>
The <body> element defines the body of the HTML document.
The element has a start tag <body> and an end tag </body>.
The element content is another HTML element (a p element).
The <html> element:
<html>

<body>
<p>This is my first paragraph.</p>
</body>

</html>
The <html> element defines the whole HTML document.
The element has a start tag <html> and an end tag </html>.
The element content is another HTML element (the body element).

Don't Forget the End Tag

Some HTML elements might display correctly even if you forget the end tag:
<p>This is a paragraph
<p>This is a paragraph
The example above works in most browsers, because the closing tag is considered optional.
Never rely on this. Many HTML elements will produce unexpected results and/or errors if you forget the end tag .

Empty HTML Elements

HTML elements with no content are called empty elements.
<br> is an empty element without a closing tag (the <br> tag defines a line break).
Tip: In XHTML, all elements must be closed. Adding a slash inside the start tag, like <br />, is the proper way of closing empty elements in XHTML (and XML).

HTML Tip: Use Lowercase Tags

HTML tags are not case sensitive: <P> means the same as <p>. Many web sites use uppercase HTML tags.

HTML Attributes

  • HTML elements can have attributes
  • Attributes provide additional information about an element
  • Attributes are always specified in the start tag
  • Attributes come in name/value pairs like: name="value"

Attribute Example

HTML links are defined with the <a> tag. The link address is specified in the href attribute:

Example

<a href="http://www.w3schools.com">This is a link</a>




Always Quote Attribute Values

Attribute values should always be enclosed in quotes.
Double style quotes are the most common, but single style quotes are also allowed.
RemarkTip: In some rare situations, when the attribute value itself contains quotes, it is necessary to use single quotes: name='John "ShotGun" Nelson'

HTML Tip: Use Lowercase Attributes

Attribute names and attribute values are case-insensitive.
However, the World Wide Web Consortium (W3C) recommends lowercase attributes/attribute values in their HTML 4 recommendation.
Newer versions of (X)HTML will demand lowercase attributes.

HTML Attributes Reference

A complete list of legal attributes for each HTML element is listed in our:
Below is a list of some attributes that are standard for most HTML elements:
Attribute
Value
Description
class
classname
Specifies a classname for an element
id
Id
Specifies a unique id for an element
style
style_definition
Specifies an inline style for an element
title
tooltip_text 
Specifies extra information about an element (displayed as a tool tip)
For more information about standard attributes:
Headings are important in HTML documents.

HTML Headings

Headings are defined with the <h1> to <h6> tags.
<h1> defines the most important heading. <h6> defines the least important heading.

Example

<h1>This is a heading</h1>
<h2>This is a heading</h2>
<h3>This is a heading</h3>


Note: Browsers automatically add some empty space (a margin) before and after each heading.

Headings Are Important

Use HTML headings for headings only. Don't use headings to make text BIG or bold.
Search engines use your headings to index the structure and content of your web pages.
Since users may skim your pages by its headings, it is important to use headings to show the document structure.
H1 headings should be used as main headings, followed by H2 headings, then the less important H3 headings, and so on.

HTML Lines

The <hr /> tag creates a horizontal line in an HTML page.

The hr element can be used to separate content:

Example

<p>This is a paragraph</p>
<hr />
<p>This is a paragraph</p>
<hr />
<p>This is a paragraph</p>




HTML Comments

Comments can be inserted into the HTML code to make it more readable and understandable. Comments are ignored by the browser and are not displayed.
Comments are written like this:

Example

<!-- This is a comment -->


Note: There is an exclamation point after the opening bracket, but not before the closing bracket.

HTML Tip - How to View HTML Source

Have you ever seen a Web page and wondered "Hey! How did they do that?"
To find out, right-click in the page and select "View Source" (IE) or "View Page Source" (Firefox), or similar for other browsers. This will open a window containing the HTML code of the page.

HTML Tag Reference

W3Schools' tag reference contains additional information about these tags and their attributes.
You will learn more about HTML tags and attributes in the next chapters of this tutorial.
Tag
Description
Defines an HTML document
Defines the document's body
Defines HTML headings
Defines a horizontal line
Defines a comment

HTML Paragraphs

Paragraphs are defined with the <p> tag.

Example

<p>This is a paragraph</p>
<p>This is another paragraph</p>


Note: Browsers automatically add an empty line before and after a paragraph.

Don't Forget the End Tag

Most browsers will display HTML correctly even if you forget the end tag:

Example

<p>This is a paragraph
<p>This is another paragraph


The example above will work in most browsers, but don't rely on it. Forgetting the end tag can produce unexpected results or errors.
Note: Future version of HTML will not allow you to skip end tags.

HTML Line Breaks

Use the <br /> tag if you want a line break (a new line) without starting a new paragraph:

Example

<p>This is<br />a para<br />graph with line breaks</p>


The <br /> element is an empty HTML element. It has no end tag.

<br> or <br />

In XHTML, XML, and future versions of HTML, HTML elements with no end tag (closing tag) are not allowed.
Even if <br> works in all browsers, writing <br /> instead is more future proof.

HTML Output - Useful Tips

You cannot be sure how HTML will be displayed. Large or small screens, and resized windows will create different results.
With HTML, you cannot change the output by adding extra spaces or extra lines in your HTML code.
The browser will remove extra spaces and extra lines when the page is displayed. Any number of lines count as one line, and any number of spaces count as one space.
 (The example demonstrates some HTML formatting problems)

HTML Tag Reference

W3Schools' tag reference contains additional information about HTML elements and their attributes.
Tag
Description
Defines a paragraph
Inserts a single line break

HTML Text Formatting

This text is bold

This text is big

This text is italic

This is computer output

This is subscript and superscript

HTML Formatting Tags

HTML uses tags like <b> and <i> for formatting output, like bold or italic text.
These HTML tags are called formatting tags (look at the bottom of this page for a complete reference).
Remark
Often <strong> renders as <b>, and <em> renders as <i>.

However, there is a difference in the meaning of these tags:

<b> or <i> defines bold or italic text only.

<strong> or <em> means that you want the text to be rendered in a way that the user understands as "important". Today, all major browsers render strong as bold and em as italics. However, if a browser one day wants to make a text highlighted with the strong feature, it might be cursive for example and not bold!

HTML Text Formatting Tags         

Tag
Description
Defines bold text
Defines big text
Defines emphasized text 
Defines italic text
Defines small text
Defines strong text
Defines subscripted text
Defines superscripted text
Defines inserted text
Defines deleted text

HTML "Computer Output" Tags

Tag
Description
Defines computer code text
Defines keyboard text 
Defines sample computer code
Defines teletype text
Defines a variable
Defines preformatted text

HTML Citations, Quotations, and Definition Tags

Tag
Description
Defines an abbreviation
Defines an acronym
Defines contact information for the author/owner of a document
Defines the text direction
Defines a long quotation
Defines a short quotation
Defines a citation
Defines a definition term

The HTML <font> Tag Should NOT be Used

The <font> tag is deprecated in HTML 4, and removed from HTML5.
The World Wide Web Consortium (W3C) has removed the <font> tag from its recommendations.
In HTML 4, style sheets (CSS) should be used to define the layout and display properties for many HTML elements.
The example below shows how the HTML could look by using the <font> tag:

Example

<p>
<font size="5" face="arial" color="red">
This paragraph is in Arial, size 5, and in red text color.
</font>
</p>

<p>
<font size="3" face="verdana" color="blue">
This paragraph is in Arial, size 5, and in red text color.
</font>
</p>
CSS is used to style HTML elements.

Look! Styles and colors

This text is in Verdana and red
This text is in Times and blue
This text is 30 pixels high

Styling HTML with CSS

CSS was introduced together with HTML 4, to provide a better way to style HTML elements.
CSS can be added to HTML in the following ways:
  • in separate style sheet files (CSS files)
  • in the style element in the HTML head section
  • in the style attribute in single HTML elements

Using the HTML Style Attribute

It is time consuming and not very practical to style HTML elements using the style attribute.
The preferred way to add CSS to HTML, is to put CSS syntax in separate CSS files.
However, in this HTML tutorial we will introduce you to CSS using the style attribute. This is done to simplify the examples. It also makes it easier for you to edit the code and try it yourself.

HTML Style Example - Background Color

The background-color property defines the background color for an element:

Example

<html>

<body style="background-color:yellow;">
<h2 style="background-color:red;">This is a heading</h2>
<p style="background-color:green;">This is a paragraph.</p>
</body>

</html>


The background-color property makes the "old" bgcolor attribute obsolete.

HTML Style Example - Font, Color and Size

The font-family, color, and font-size properties defines the font, color, and size of the text in an element:

Example

<html>

<body>
<h1 style="font-family:verdana;">A heading</h1>
<p style="font-family:arial;color:red;font-size:20px;">A paragraph.</p>
</body>

</html>
The font-family, color, and font-size properties make the old <font> tag obsolete.

HTML Style Example - Text Alignment

The text-align property specifies the horizontal alignment of text in an element:

Example

<html>

<body>
<h1 style="text-align:center;">Center-aligned heading</h1>
<p>This is a paragraph.</p>
</body>

</html>
The text-align property makes the old <center> tag obsolete.

Deprecated Tags and Attributes

In HTML 4, several tags and attributes were deprecated. Deprecated means that they will not be supported in future versions of HTML.
RemarkThe message is clear: Avoid using deprecated tags and attributes!
These tags and attributes should be avoided:
Tags
Description
<center>
Deprecated. Defines centered content
<font> and <basefont>
Deprecated. Defines HTML fonts
<s> and <strike>
Deprecated. Defines strikethrough text
<u>
Deprecated. Defines underlined text
Attributes
Description
align
Deprecated. Defines the alignment of text
bgcolor
Deprecated. Defines the background color
color
Deprecated. Defines the text color

HTML Hyperlinks (Links)

A hyperlink (or link) is a word, group of words, or image that you can click on to jump to a new document or a new section within the current document.
When you move the cursor over a link in a Web page, the arrow will turn into a little hand.
Links are specified in HTML using the <a> tag.
The <a> tag can be used in two ways:
  1. To create a link to another document, by using the href attribute
  2. To create a bookmark inside a document, by using the name attribute

HTML Link Syntax

The HTML code for a link is simple. It looks like this:
<a href="url">Link text</a>
The href attribute specifies the destination of a link.

Example

<a href="http://www.w3schools.com/">Visit W3Schools</a>
Tip: The "Link text" doesn't have to be text. You can link from an image or any other HTML element.

HTML Links - The target Attribute

The target attribute specifies where to open the linked document.
The example below will open the linked document in a new browser window or a new tab:

Example

<a href="http://www.w3schools.com/" target="_blank">Visit W3Schools!</a>




HTML Links - The name Attribute

The name attribute specifies the name of an anchor.

The name attribute is used to create a bookmark inside an HTML document.
Note:
The upcoming HTML5 standard suggest using the id attribute instead of the name attribute for specifying the name of an anchor.
Using the id attribute actually works also for HTML4 in all modern browsers.
Bookmarks are not displayed in any special way. They are invisible to the reader.

Example

A named anchor inside an HTML document:
<a name="tips">Useful Tips Section</a>
Create a link to the "Useful Tips Section" inside the same document:
<a href="#tips">Visit the Useful Tips Section</a>
Or, create a link to the "Useful Tips Section" from another page:
<a href="http://www.w3schools.com/html_links.htm#tips">
Visit the Useful Tips Section</a>

HTML Images - The <img> Tag and the Src Attribute

In HTML, images are defined with the <img> tag. 
The <img> tag is empty, which means that it contains attributes only, and has no closing tag.
To display an image on a page, you need to use the src attribute. Src stands for "source". The value of the src attribute is the URL of the image you want to display.
Syntax for defining an image:
<img src="url" alt="some_text"/>
The URL points to the location where the image is stored. An image named "boat.gif", located in the "images" directory on "www.w3schools.com" has the URL: http://www.w3schools.com/images/boat.gif.
The browser displays the image where the <img> tag occurs in the document. If you put an image tag between two paragraphs, the browser shows the first paragraph, then the image, and then the second paragraph.

HTML Images - The Alt Attribute

The required alt attribute specifies an alternate text for an image, if the image cannot be displayed.
The value of the alt attribute is an author-defined text:
<img src="boat.gif" alt="Big Boat" />
The alt attribute provides alternative information for an image if a user for some reason cannot view it (because of slow connection, an error in the src attribute, or if the user uses a screen reader).

HTML Images - Set Height and Width of an Image

The height and width attributes are used to specify the height and width of an image.
The attribute values are specified in pixels by default:
<img src="pulpit.jpg" alt="Pulpit rock" width="304" height="228" />
Tip: It is a good practice to specify both the height and width attributes for an image. If these attributes are set, the space required for the image is reserved when the page is loaded. However, without these attributes, the browser does not know the size of the image. The effect will be that the page layout will change during loading (while the images load).

Basic Notes - Useful Tips

Note: If an HTML file contains ten images - eleven files are required to display the page right. Loading images take time, so my best advice is: Use images carefully.
Note: When a web page is loaded, it is the browser, at that moment, that actually gets the image from a web server and inserts it into the page. Therefore, make sure that the images actually stay in the same spot in relation to the web page, otherwise your visitors will get a broken link icon. The broken link icon is shown if the browser cannot find the image.

HTML Image Tags

Tag
Description
Defines an image
Defines an image-map
Defines a clickable area inside an image-map

HTML Tables

Tables are defined with the <table> tag.
A table is divided into rows (with the <tr> tag), and each row is divided into data cells (with the <td> tag). td stands for "table data," and holds the content of a data cell. A <td> tag can contain text, links, images, lists, forms, other tables, etc.

Table Example

<table border="1">
<tr>
<td>row 1, cell 1</td>
<td>row 1, cell 2</td>
</tr>
<tr>
<td>row 2, cell 1</td>
<td>row 2, cell 2</td>
</tr>
</table>
How the HTML code above looks in a browser:
row 1, cell 1
row 1, cell 2
row 2, cell 1
row 2, cell 2


HTML Tables and the Border Attribute

If you do not specify a border attribute, the table will be displayed without borders. Sometimes this can be useful, but most of the time, we want the borders to show.
To display a table with borders, specify the border attribute:
<table border="1">
<tr>
<td>Row 1, cell 1</td>
<td>Row 1, cell 2</td>
</tr>
</table>


HTML Table Headers

Header information in a table are defined with the <th> tag.
All major browsers will display the text in the <th> element as bold and centered.
<table border="1">
<tr>
<th>Header 1</th>
<th>Header 2</th>
</tr>
<tr>
<td>row 1, cell 1</td>
<td>row 1, cell 2</td>
</tr>
<tr>
<td>row 2, cell 1</td>
<td>row 2, cell 2</td>
</tr>
</table>
How the HTML code above looks in your browser:
Header 1
Header 2
row 1, cell 1
row 1, cell 2
row 2, cell 1
row 2, cell 2

HTML Table Tags

Tag
Description
Defines a table
Defines a table header
Defines a table row
Defines a table cell
Defines a table caption
Defines a group of columns in a table, for formatting
Defines attribute values for one or more columns in a table
Groups the header content in a table
Groups the body content in a table
Groups the footer content in a table
The most common HTML lists are ordered and unordered lists:

HTML Lists

An ordered list:

  1. The first list item
  2. The second list item
  3. The third list item

An unordered list:

  • List item
  • List item
  • List item

HTML Unordered Lists

An unordered list starts with the <ul> tag. Each list item starts with the <li> tag.
The list items are marked with bullets (typically small black circles).
<ul>
<li>Coffee</li>
<li>Milk</li>
</ul>
How the HTML code above looks in a browser:
  • Coffee
  • Milk

HTML Ordered Lists

An ordered list starts with the <ol> tag. Each list item starts with the <li> tag.
The list items are marked with numbers.
<ol>
<li>Coffee</li>
<li>Milk</li>
</ol>
How the HTML code above looks in a browser:
  1. Coffee
  2. Milk

HTML Definition Lists

A definition list is a list of items, with a description of each item.
The <dl> tag defines a definition list.
The <dl> tag is used in conjunction with <dt> (defines the item in the list) and <dd> (describes the item in the list):
<dl>
<dt>Coffee</dt>
<dd>- black hot drink</dd>
<dt>Milk</dt>
<dd>- white cold drink</dd>
</dl>
How the HTML code above looks in a browser:
Coffee
- black hot drink
Milk
- white cold drink

HTML List Tags

Tag
Description
Defines an ordered list
Defines an unordered list
Defines a list item
Defines a definition list
Defines an item in a definition list
Defines a description of an item in a definition list

HTML Forms

HTML forms are used to pass data to a server.
A form can contain input elements like text fields, checkboxes, radio-buttons, submit buttons and more. A form can also contain select lists, textarea, fieldset, legend, and label elements.
The <form> tag is used to create an HTML form:
<form>
.
input elements
.
</form>


HTML Forms - The Input Element

The most important form element is the input element.
The input element is used to select user information.
An input element can vary in many ways, depending on the type attribute. An input element can be of type text field, checkbox, password, radio button, submit button, and more.
The most used input types are described below.

Text Fields

<input type="text" /> defines a one-line input field that a user can enter text into:
<form>
First name: <input type="text" name="firstname" /><br />
Last name: <input type="text" name="lastname" />
</form>
How the HTML code above looks in a browser:
First name:
Last name:
Note: The form itself is not visible. Also note that the default width of a text field is 20 characters. 

Password Field

<input type="password" /> defines a password field:
<form>
Password: <input type="password" name="pwd" />
</form>
How the HTML code above looks in a browser:
Password:
Note: The characters in a password field are masked (shown as asterisks or circles). 

Radio Buttons

<input type="radio" /> defines a radio button. Radio buttons let a user select ONLY ONE one of a limited number of choices:
<form>
<input type="radio" name="sex" value="male" /> Male<br />
<input type="radio" name="sex" value="female" /> Female
</form>
How the HTML code above looks in a browser:
Male
Female

Checkboxes

<input type="checkbox" /> defines a checkbox. Checkboxes let a user select ONE or MORE options of a limited number of choices.
<form>
<input type="checkbox" name="vehicle" value="Bike" /> I have a bike<br />
<input type="checkbox" name="vehicle" value="Car" /> I have a car
</form>
How the HTML code above looks in a browser:
I have a bike
I have a car

Submit Button

<input type="submit" /> defines a submit button.
A submit button is used to send form data to a server. The data is sent to the page specified in the form's action attribute. The file defined in the action attribute usually does something with the received input:
<form name="input" action="html_form_action.asp" method="get">
Username: <input type="text" name="user" />
<input type="submit" value="Submit" />
</form>
How the HTML code above looks in a browser:
Username:
If you type some characters in the text field above, and click the "Submit" button, the browser will send your input to a page called "html_form_action.asp". The page will show you the received input.

HTML Form Tags

Tag
Description
Defines an HTML form for user input
Defines an input control
Defines a multi-line text input control
Defines a label for an input element
Defines a border around elements in a form
Defines a caption for a fieldset element
Defines a select list (drop-down list)
Defines a group of related options in a select list
Defines an option in a select list
Defines a push button

HTML Frames

With frames, you can display more than one HTML document in the same browser window. Each HTML document is called a frame, and each frame is independent of the others.
The disadvantages of using frames are:
  • Frames are not expected to be supported in future versions of HTML
  • Frames are difficult to use. (Printing the entire page is difficult).
  • The web developer must keep track of more HTML documents

The HTML frameset Element

The frameset element holds one or more frame elements. Each frame element can hold a separate document.
The frameset element states HOW MANY columns or rows there will be in the frameset, and HOW MUCH percentage/pixels of space will occupy each of them.

The HTML frame Element

The <frame> tag defines one particular window (frame) within a frameset.
In the example below we have a frameset with two columns.
The first column is set to 25% of the width of the browser window. The second column is set to 75% of the width of the browser window. The document "frame_a.htm" is put into the first column, and the document "frame_b.htm" is put into the second column:
<frameset cols="25%,75%">
   <frame src="frame_a.htm" />
   <frame src="frame_b.htm" />
</frameset>
Note: The frameset column size can also be set in pixels (cols="200,500"), and one of the columns can be set to use the remaining space, with an asterisk (cols="25%,*").

HTML Frame Tags

Tag
Description
Defines a set of frames
Defines a sub window (a frame)
Defines a noframe section for browsers that do not handle frames
Syntax for adding an iframe:
<iframe src="URL"></iframe>
The URL points to the location of the separate page.

Iframe - Set Height and Width

The height and width attributes are used to specify the height and width of the iframe.
The attribute values are specified in pixels by default, but they can also be in percent (like "80%").

Example

<iframe src="demo_iframe.htm" width="200" height="200"></iframe>


Iframe - Remove the Border

The frameborder attribute specifies whether or not to display a border around the iframe.
Set the attribute value to "0" to remove the border:

Example

<iframe src="demo_iframe.htm" frameborder="0"></iframe>


Use iframe as a Target for a Link

An iframe can be used as the target frame for a link.
The target attribute of a link must refer to the name attribute of the iframe:

Example

<iframe src="demo_iframe.htm" name="iframe_a"></iframe>
<p><a href="http://www.w3schools.com" target="iframe_a">W3Schools.com</a></p>


HTML iframe Tag

Tag
Description
Defines an inline sub window (frame)
Colors are displayed combining RED, GREEN, and BLUE light.

Color Values

HTML colors are defined using a hexadecimal notation (HEX) for the combination of Red, Green, and Blue color values (RGB).
The lowest value that can be given to one of the light sources is 0 (in HEX: 00). The highest value is 255 (in HEX: FF).

HTML Basic Document

<html>
<head>
<title>Title of document goes here</title>
</head>
<body>
Visible text goes here...
</body>
</html>

Heading Elements

<h1>Largest Heading</h1>
<h2> . . . </h2>
<h3> . . . </h3>
<h4> . . . </h4>
<h5> . . . </h5>
<h6>Smallest Heading</h6>

Text Elements

<p>This is a paragraph</p>
<br /> (line break)
<hr /> (horizontal rule)
<pre>This text is preformatted</pre>

Logical Styles

<em>This text is emphasized</em>
<strong>This text is strong</strong>
<code>This is some computer code</code>

Physical Styles

<b>This text is bold</b>
<i>This text is italic</i>

Links

Ordinary link: <a href="http://www.example.com/">Link-text goes here</a>
Image-link: <a href="http://www.example.com/"><img src="URL" alt="Alternate Text" /></a>
Mailto link: <a href="mailto:webmaster@example.com">Send e-mail</a>
A named anchor:
<a name="tips">Tips Section</a>
<a href="#tips">Jump to the Tips Section</a>

Unordered list

<ul>
  <li>Item</li>
  <li>Item</li>
</ul>

Ordered list

<ol>
  <li>First item</li>
  <li>Second item</li>
</ol>

Definition list

<dl>
  <dt>First term</dt>
    <dd>Definition</dd>
  <dt>Next term</dt>
    <dd>Definition</dd>
</dl>

Tables

<table border="1">
  <tr>
    <th>Tableheader</th>
    <th>Tableheader</th>
  </tr>
  <tr>
    <td>sometext</td>
    <td>sometext</td>
  </tr>
</table>

Frames

<frameset cols="25%,75%">
  <frame src="page1.htm" />
  <frame src="page2.htm" />
</frameset>

Forms

<form action="http://www.example.com/test.asp" method="post/get">
<input type="text" name="email" size="40" maxlength="50" />
<input type="password" />
<input type="checkbox" checked="checked" />
<input type="radio" checked="checked" />
<input type="submit" value="Send" />
<input type="reset" />
<input type="hidden" />

<select>
<option>Apples</option>
<option selected="selected">Bananas</option>
<option>Cherries</option>
</select>
<textarea name="comment" rows="60" cols="20"></textarea>

</form>

Entities

&lt; is the same as <
&gt; is the same as >
&#169; is the same as ©

Other Elements

<!-- This is a comment -->
<blockquote>
Text quoted from a source.
</blockquote>
<address>
Written by W3Schools.com<br />
<a href="mailto:us@example.org">Email us</a><br />
Address: Box 564, Disneyland<br />
Phone: +12 34 56 78
</address>

Website Layouts

Most websites have put their content in multiple columns (formatted like a magazine or newspaper).
Multiple columns is created by using <table> or <div> tags. Some CSS are normally also added to position elements, or to create backgrounds or colorful look for the pages.

HTML Layouts - Using Tables

The simplest way of creating layouts is by using the HTML <table> tag.
The following example uses a table with 3 rows and 2 columns - the first and last row spans both columns using the colspan attribute:

Example

<html>
<body>

<table width="500" border="0">
<tr>
<td colspan="2" style="background-color:#FFA500;">
<h1>Main Title of Web Page</h1>
</td>
</tr>

<tr valign="top">
<td style="background-color:#FFD700;width:100px;text-align:top;">
<b>Menu</b><br />
HTML<br />
CSS<br />
JavaScript
</td>
<td style="background-color:#EEEEEE;height:200px;width:400px;text-align:top;">
Content goes here</td>
</tr>

<tr>
<td colspan="2" style="background-color:#FFA500;text-align:center;">
Copyright © 2011 W3Schools.com</td>
</tr>
</table>

</body>
</html>


The HTML code above will produce the following result:

Main Title of Web Page

Menu
HTML
CSS
JavaScript
Content goes here
Copyright © 2011 W3Schools.com
RemarkNote: Even though it is possible to create nice layouts with HTML tables, tables were designed for presenting tabular data - NOT as a layout tool!

HTML Layouts - Using Div Elements

The div element is a block level element used for grouping HTML elements.
The following example uses five div elements to create a multiple column layout, creating the same result as in the previous example:

Example

<html>
<body>

<div id="container" style="width:500px">

<div id="header" style="background-color:#FFA500;">
<h1 style="margin-bottom:0;">Main Title of Web Page</h1></div>

<div id="menu" style="background-color:#FFD700;height:200px;width:100px;float:left;">
<b>Menu</b><br />
HTML<br />
CSS<br />
JavaScript</div>

<div id="content" style="background-color:#EEEEEE;height:200px;width:400px;float:left;">
Content goes here</div>

<div id="footer" style="background-color:#FFA500;clear:both;text-align:center;">
Copyright © 2011 W3Schools.com</div>

</div>

</body>
</html>
The HTML code above will produce the following result:

Main Title of Web Page

Menu
HTML
CSS
JavaScript
Content goes here
Copyright © 2011 W3Schools.com


HTML Layout - Useful Tips

Tip: The biggest advantage of using CSS is that, if you place the CSS code in an external style sheet, your site becomes MUCH EASIER to maintain. You can change the layout of all your pages by editing one file. To learn more about CSS,
Tip: Because advanced layouts take time to create, a quicker option is to use a template. Search Google for free website templates (these are pre-built website layouts you can use and customize).

HTML Layout Tags

Tag
Description
Defines a table
Defines a section in a document

HTML Doctypes




A doctype declaration refers to the rules for the markup language, so that the browsers render the content correctly.

Example

An HTML document with a doctype of HTML 4.01 Transitional:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Title of the document</title>
</head>

<body>
The content of the document......
</body>

</html>

HTML Different Doctypes

The doctype declaration is not an HTML tag; it is an instruction to the web browser about what version of the markup language the page is written in.
The doctype declaration refers to a Document Type Definition (DTD). The DTD specifies the rules for the markup language, so that the browsers render the content correctly.
The doctype declaration should be the very first thing in an HTML document, before the <html> tag.
RemarkTip: Always add a doctype to your pages. This helps the browsers to render the page correctly!

HTML 4.01 Strict

This DTD contains all HTML elements and attributes, but does NOT INCLUDE presentational or deprecated elements (like font and center). Framesets are not allowed:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">

HTML 4.01 Transitional

This DTD contains all HTML elements and attributes, INCLUDING presentational and deprecated elements (like font). Framesets are not allowed:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">

HTML 4.01 Frameset

This DTD is equal to HTML 4.01 Transitional, but allows the use of frameset content:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN"
"http://www.w3.org/TR/html4/frameset.dtd">


Tips and Notes


HTML DOCTYPE Element

Tag
Description
Defines the document type. This declaration goes before the <html> start tag

How to Use Styles

When a browser reads a style sheet, it will format the document according to it.
There are three ways of inserting a style sheet:
  • External style sheet
  • Internal style sheet
  • Inline styles

External Style Sheet

An external style sheet is ideal when the style is applied to many pages. With an external style sheet, you can change the look of an entire Web site by changing one file. Each page must link to the style sheet using the <link> tag. The <link> tag goes inside the <head> section:
<head>
<link rel="stylesheet" type="text/css" href="mystyle.css" />
</head>


Internal Style Sheet

An internal style sheet can be used if one single document has a unique style. Internal styles are defined in the <head> section of an HTML page, by using the <style> tag, like this:
<head>
<style type="text/css">
body {background-color:yellow;}
p {color:blue;}
</style>
</head>


Inline Styles

An inline style can be used if a unique style is to be applied to one single occurrence of an element.
To use inline styles, use the style attribute in the relevant tag. The style attribute can contain any CSS property. The example below shows how to change the text color and the left margin of a paragraph:
<p style="color:blue;margin-left:20px;">This is a paragraph.</p>
To learn more about style sheets, visit our CSS tutorial.

HTML Style Tags

Tag
Description
Defines style information for a document
Defines the relationship between a document and an external resource

The HTML head Element

The head element is a container for all the head elements. Elements inside <head> can include scripts, instruct the browser where to find style sheets, provide meta information, and more.
The following tags can be added to the head section: <title>, <base>, <link>, <meta>, <script>, and <style>.

The HTML title Element

The <title> tag defines the title of the document.
The title element is required in all HTML/XHTML documents.
The title element:
  • defines a title in the browser toolbar
  • provides a title for the page when it is added to favorites
  • displays a title for the page in search-engine results
A simplified HTML document:
<html>
<head>
<title>Title of the document</title>
</head>

<body>
The content of the document......
</body>

</html>


The HTML base Element

The <base> tag specifies a default address or a default target for all links on a page:
<head>
<base href="http://www.w3schools.com/images/" />
<base target="_blank" />
</head>


The HTML link Element

The <link> tag defines the relationship between a document and an external resource.
The <link> tag is most used to link to style sheets:
<head>
<link rel="stylesheet" type="text/css" href="mystyle.css" />
</head>


The HTML style Element

The <style> tag is used to define style information for an HTML document.
Inside the style element you specify how HTML elements should render in a browser:
<head>
<style type="text/css">
body {background-color:yellow}
p {color:blue}
</style>
</head>


The HTML meta Element

The <meta> tag provides metadata about the HTML document.
The meta element will be explained in the next chapter.

The HTML script Element

The <script> tag is used to define a client-side script, such as a JavaScript.
The script element will be explained in a later chapter.

HTML head Elements

Tag
Description
Defines information about the document
Defines the title of a document
Defines a default address or a default target for all links on a page
Defines the relationship between a document and an external resource
Defines metadata about an HTML document
Defines a client-side script
Defines style information for a document

The HTML meta Element

Metadata is information about data.
The <meta> tag provides metadata about the HTML document. Metadata will not be displayed on the page, but will be machine parsable.
Meta elements are typically used to specify page description, keywords, author of the document, last modified, and other metadata.
The <meta> tag always goes inside the head element.
The metadata can be used by browsers (how to display content or reload page), search engines (keywords), or other web services.

Keywords for Search Engines

Some search engines will use the name and content attributes of the meta element to index your pages.
The following meta element defines a description of a page:
<meta name="description" content="Free Web tutorials on HTML, CSS, XML" />
The following meta element defines keywords for a page:
<meta name="keywords" content="HTML, CSS, XML" />
The intention of the name and content attributes is to describe the content of a page.
RemarkNote: A lot of webmasters have used <meta> tags for spamming, like repeating keywords (or using wrong keywords) for higher ranking. Therefore, most search engines have stopped using <meta> tags to index/rank pages.

The HTML script Element

The <script> tag is used to define a client-side script, such as a JavaScript.
The script element either contains scripting statements or it points to an external script file through the src attribute.
The required type attribute specifies the MIME type of the script.
Common uses for JavaScript are image manipulation, form validation, and dynamic changes of content.
The script below writes Hello World! to the HTML output:

Example

<script type="text/javascript">
document.write("Hello World!")
</script>



The HTML noscript Element

The <noscript> tag is used to provide an alternate content for users that have disabled scripts in their browser or have a browser that doesn’t support client-side scripting.
The noscript element can contain all the elements that you can find inside the body element of a normal HTML page.
The content inside the noscript element will only be displayed if scripts are not supported, or are disabled in the user’s browser:

Example

<script type="text/javascript">
document.write("Hello World!")
</script>
<noscript>Sorry, your browser does not support JavaScript!</noscript>




HTML Script Tags

Tag
Description
Defines a client-side script
Defines an alternate content for users that do not support client-side scripts

Hosting your own Web site

Hosting your web site on your own server is always an option. Here are some points to consider:

Hardware Expenses

To run a "real" web site, you will have to buy some powerful server hardware. Don't expect that a low cost PC will do the job. You will also need a permanent (24 hours a day ) high-speed connection.

Software Expenses

Remember that server-licenses often are higher than client-licenses. Also note that server-licenses might have limits on number of users.

Labor Expenses

Don't expect low labor expenses. You have to install your own hardware and software. You also have to deal with bugs and viruses, and keep your server constantly running in an environment where "everything could happen".

Using an Internet Service Provider

Renting a server from an Internet Service Provider (ISP) is a common option.
Most small companies store their web site on a server provided by an ISP. Here are some advantages:

Connection Speed

Most ISPs have very fast connections to the Internet.

Powerful Hardware

ISPs often have powerful web servers that can be shared by several companies. You can also expect them to have an effective load balancing, and necessary backup servers.

Security and Stability

ISPs are specialists on web hosting. Expect their servers to have more than 99% up time, the latest software patches, and the best virus protection.

Things to Consider with an ISP

24-hour support

Make sure your ISP offers 24-hours support. Don't put yourself in a situation where you cannot fix critical problems without having to wait until the next working day. Toll-free phone could be vital if you don't want to pay for long distance calls.

Daily Backup

Make sure your ISP runs a daily backup routine, otherwise you may lose some valuable data.

Traffic Volume

Study the ISP's traffic volume restrictions. Make sure that you don't have to pay a fortune for unexpected high traffic if your web site becomes popular.

Bandwidth or Content Restrictions

Study the ISP's bandwidth and content restrictions. If you plan to publish pictures or broadcast video or sound, make sure that you can.

E-mail Capabilities

Make sure your ISP supports the e-mail capabilities you need.

Database Access

If you plan to use data from databases on your web site, make sure your ISP supports the database access you need.

Ordered Alphabetically

DTD: indicates in which HTML 4.01 / XHTML 1.0 DTD the tag is allowed. S=Strict, T=Transitional, and F=Frameset
Tag
Description
DTD
Defines a comment
STF
Defines the document type
STF
Defines an anchor
STF
Defines an abbreviation
STF
Defines an acronym
STF
Defines contact information for the author/owner of a document
STF
Deprecated. Defines an embedded applet
TF
Defines an area inside an image-map
STF
Defines bold text
STF
Defines a default address or a default target for all links on a page
STF
Deprecated. Defines a default font, color, or size for the text in a page
TF
Defines the text direction
STF
Defines big text
STF
Defines a long quotation
STF
Defines the document's body
STF
Defines a single line break
STF
Defines a push button
STF
Defines a table caption
STF
Deprecated. Defines centered text
TF
Defines a citation
STF
Defines computer code text
STF
Defines attribute values for one or more columns in a table 
STF
Defines a group of columns in a table for formatting
STF
Defines a description of a term in a definition list
STF
Defines deleted text
STF
Defines a definition term
STF
Deprecated. Defines a directory list
TF
Defines a section in a document
STF
Defines a definition list
STF
Defines a term (an item) in a definition list
STF
Defines emphasized text 
STF
Defines a border around elements in a form
STF
Deprecated. Defines font, color, and size for text
TF
Defines an HTML form for user input
STF
Defines a window (a frame) in a frameset
F
Defines a set of frames
F
Defines HTML headings
STF
Defines information about the document
STF
Defines a horizontal line
STF
Defines an HTML document
STF
Defines italic text
STF
Defines an inline frame
TF
Defines an image
STF
Defines an input control
STF
Defines inserted text
STF
<isindex>
Deprecated. Defines a searchable index related to a document
TF
Defines keyboard text
STF
Defines a label for an input element
STF
Defines a caption for a fieldset element
STF
Defines a list item
STF
Defines the relationship between a document and an external resource
STF
Defines an image-map 
STF
Deprecated. Defines a menu list
TF
Defines metadata about an HTML document
STF
Defines an alternate content for users that do not support frames
TF
Defines an alternate content for users that do not support client-side scripts
STF
Defines an embedded object
STF
Defines an ordered list
STF
Defines a group of related options in a select list
STF
Defines an option in a select list
STF
Defines a paragraph
STF
Defines a parameter for an object
STF
Defines preformatted text
STF
Defines a short quotation
STF
Deprecated. Defines strikethrough text
TF
Defines sample computer code
STF
Defines a client-side script
STF
Defines a select list (drop-down list)
STF
Defines small text
STF
Defines a section in a document
STF
Deprecated. Defines strikethrough text
TF
Defines strong text
STF
Defines style information for a document
STF
Defines subscripted text
STF
Defines superscripted text
STF
Defines a table
STF
Groups the body content in a table
STF
Defines a cell in a table
STF
Defines a multi-line text input control
STF
Groups the footer content in a table
STF
Defines a header cell in a table
STF
Groups the header content in a table
STF
Defines the title of a document
STF
Defines a row in a table
STF
Defines teletype text
STF
Deprecated. Defines underlined text
TF
Defines an unordered list
STF
Defines a variable part of a text
STF
<xmp>
Deprecated. Defines preformatted text

Ordered by Function

DTD: indicates in which HTML 4.01 / XHTML 1.0 DTD the tag is allowed. S=Strict, T=Transitional, and F=Frameset
Tag
Description
DTD
Basic


Defines the document type
STF
Defines an HTML document
STF
Defines the document's body
STF
Defines HTML headings
STF
Defines a paragraph
STF
Inserts a single line break
STF
Defines a horizontal line
STF
Defines a comment
STF
Formatting


Defines an acronym
STF
Defines an abbreviation
STF
Defines contact information for the author/owner of a document
STF
Defines bold text
STF
Defines the text direction
STF
Defines big text
STF
Defines a long quotation
STF
Deprecated. Defines centered text
TF
Defines a citation
STF
Defines computer code text
STF
Defines deleted text
STF
Defines a definition term
STF
Defines emphasized text 
STF
Deprecated. Defines font, color, and size for text
TF
Defines italic text
STF
Defines inserted text
STF
Defines keyboard text
STF
Defines preformatted text
STF
Defines a short quotation
STF
Deprecated. Defines strikethrough text
TF
Defines sample computer code
STF
Defines small text
STF
Deprecated. Defines strikethrough text
TF
Defines strong text
STF
Defines subscripted text
STF
Defines superscripted text
STF
Defines teletype text
STF
Deprecated. Defines underlined text
TF
Defines a variable part of a text
STF
<xmp>
Deprecated. Defines preformatted text

Forms


Defines an HTML form for user input
STF
Defines an input control
STF
Defines a multi-line text input control
STF
Defines a push button
STF
Defines a select list (drop-down list)
STF
Defines a group of related options in a select list
STF
Defines an option in a select list
STF
Defines a label for an input element
STF
Defines a border around elements in a form
STF
Defines a caption for a fieldset element
STF
<isindex>
Deprecated. Defines a searchable index related to a document
TF
Frames


Defines a window (a frame) in a frameset
F
Defines a set of frames
F
Defines an alternate content for users that do not support frames
TF
Defines an inline frame
TF
Images


Defines an image
STF
Defines an image-map 
STF
Defines an area inside an image-map
STF
Links


Defines an anchor
STF
Defines the relationship between a document and an external resource
STF
Lists


Defines an unordered list
STF
Defines an ordered list
STF
Defines a list item
STF
Deprecated. Defines a directory list
TF
Defines a definition list
STF
Defines a term (an item) in a definition list
STF
Defines a description of a term in a definition list
STF
Deprecated. Defines a menu list
TF
Tables


Defines a table
STF
Defines a table caption
STF
Defines a header cell in a table
STF
Defines a row in a table
STF
Defines a cell in a table
STF
Groups the header content in a table
STF
Groups the body content in a table
STF
Groups the footer content in a table
STF
Defines attribute values for one or more columns in a table
STF
Defines a group of columns in a table for formatting
STF
Styles


Defines style information for a document
STF
Defines a section in a document
STF
Defines a section in a document
STF
Meta Info


Defines information about the document
STF
Defines the document title
STF
Defines metadata about an HTML document
STF
Defines a default address or a default target for all links on a page
STF
Deprecated. Defines a default font, color, or size for the text in a page
TF
Programming


Defines a client-side script
STF
Defines an alternate content for users that do not support client-side scripts
STF
Deprecated. Defines an embedded applet
TF
Defines an embedded object
STF
Defines a parameter for an object

The attributes listed below are standard, and are supported by all HTML and XHTML tags, with a few exceptions.

Core Attributes

Not valid in base, head, html, meta, param, script, style, and title elements.
Attribute
Value
Description
classname
Specifies a classname for an element
id
Specifies a unique id for an element
style_definition
Specifies an inline style for an element
text 
Specifies extra information about an element


Language Attributes

Not valid in base, br, frame, frameset, hr, iframe, param, and script elements.
Attribute
Value
Description
dir
ltr
rtl
Specifies the text direction for the content in an element
lang
language_code
Specifies a language code for the content in an element. Language code reference
xml:lang
language_code
Specifies a language code for the content in an element, in XHTML documents. Language code reference


Keyboard Attributes

Attribute
Value
Description
accesskey
character
Specifies a keyboard shortcut to access an element
tabindex
number
Specifies the tab order of an element

bStandard Event Attributes

HTML 4 added the ability to let events trigger actions in a browser, like starting a JavaScript when a user clicks on an element.
To learn more about programming events, please visit our JavaScript tutorial and our DHTML tutorial.
Below is the standard event attributes that can be inserted into HTML / XHTML elements to define event actions.

<body> and <frameset> Events

The two attributes below can only be used in <body> or <frameset>:
Attribute
Value
Description
onload
script
Script to be run when a document load
onunload
script
Script to be run when a document unload


Form Events

The attributes below can be used in form elements:
Attribute
Value
Description
onblur
script
Script to be run when an element loses focus
onchange
script
Script to be run when an element changes
onfocus
script
Script to be run when an element gets focus
onreset
script
Script to be run when a form is reset
onselect
script
Script to be run when an element is selected
onsubmit
script
Script to be run when a form is submitted


Image Events

The attribute below can be used with the img element:
Attribute
Value
Description
onabort
script
Script to be run when loading of an image is interrupted


Keyboard Events

Valid in all elements except base, bdo, br, frame, frameset, head, html, iframe, meta, param, script, style, and title.
Attribute
Value
Description
onkeydown
script
Script to be run when a key is pressed
onkeypress
script
Script to be run when a key is pressed and released
onkeyup
script
Script to be run when a key is released


Mouse Events

Valid in all elements except base, bdo, br, frame, frameset, head, html, iframe, meta, param, script, style, and title.
Attribute
Value
Description
onclick
script
Script to be run on a mouse click
ondblclick
script
Script to be run on a mouse double-click
onmousedown
script
Script to be run when mouse button is pressed
onmousemove
script
Script to be run when mouse pointer moves
onmouseout
script
Script to be run when mouse pointer moves out of an element
onmouseover
script
Script to be run when mouse pointer moves over an element
onmouseup
script
Script to be run when mouse button is released


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Life Infotech now a leading brand in the field of technology training

  Life Infotech now a leading brand in the field of technology training & its invites students around the nation to be a part of the Tra...