Introduction to World Wide Web and HTML
What is the World Wide Web?          The World Wide Web (WWW) is most often called the Web. The Web is a network of computers all over the world. All the computers in the Web can communicate with each other. All the computers use a communication standard called HTTP. Web information is stored in documents called Web pages. Web pages are files stored on computers called Web servers. Computers reading the Web pages are called Web clients. Web clients view the pages with a program called a Web browser. Popular browsers are Internet Explorer and Netscape Navigator.

How does the WWW work?

How does the browser fetch the pages?    A browser fetches a Web page from a server by a request. A request is a standard HTTP request containing a page address. A page address looks like this: http://www.someone.com/page.htm.

How does the browser display the pages?     All Web pages contain instructions for display The browser displays the page by reading these instructions. The most common display instructions are called HTML tags. HTML tags look like this <p>This is a Paragraph</p>.

Who is making the Web standards?       Netscape or Microsoft does not make up the Web standards. The rule-making body of the Web is the W3C. W3C stands for the World Wide Web Consortium. W3C puts together specifications for Web standards. The most essential Web standards are HTML, CSS and XML. The latest HTML standard is XHTML 1.0.

Introduction to HTML What is an HTML File?      HTML stands for Hyper Text Markup Language An HTML file is a text file containing small markup tags The markup tags tell the Web browser how to display the page An HTML file must have an htm or html file extension An HTML file can be created using a simple text editor

Example 1:
Example of html file:- Type the following text in a text editor like notepad.

<html> <head> <title>Title of page</title> </head> <body> This is my first homepage. <b>This text is bold</b> </body>

</html> Save the file as "mypage.htm". Start your Internet browser. Select "Open" (or "Open Page") in the File menu of your browser. A dialog box will appear. Select "Browse" (or "Choose File") and locate the HTML file you just created - "mypage.htm" - select it and click "Open". Now you should see an address in the dialog box, for example "C:\MyDocuments\mypage.htm". Click OK, and the browser will display the page. The first tag in your HTML document is <html>. This tag tells your browser that this is the start of an HTML document. The last tag in your document is </html>. This tag tells your browser that this is the end of the HTML document. The text between the <head> tag and the </head> tag is header information. Header information is not displayed in the browser window. The text between the <title> tags is the title of your document. The title is displayed in your browser's caption. The text between the <body> tags is the text that will be displayed in your browser. The text between the <b> and </b> tags will be displayed in a bold font. HTM or HTML Extension? When you save an HTML file, you can use either the .htm or the .html extension.

HTML Elements
HTML documents are text files made up of HTML elements. HTML elements are defined using HTML tags. HTML Tags        HTML tags are used to mark-up HTML elements HTML tags are surrounded by the two characters < and > The surrounding characters are called angle brackets 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 The text between the start and end tags is the element content HTML tags are not case sensitive, <b> means the same as <B>

HTML Elements Consider the text written in example 1. This is an HTML element: <b>This text is bold</b> The HTML element starts with a start tag: <b> The content of the HTML element is: This text is bold The HTML element ends with an end tag: </b>

The purpose of the <b> tag is to define an HTML element that should be displayed as bold. This is also an HTML element: <body> This is my first homepage. <b>This text is bold</b> </body> This HTML element starts with the start tag <body>, and ends with the end tag </body>. The purpose of the <body> tag is to define the HTML element that contains the body of the HTML document. Why do We Use Lowercase Tags? We have just said that HTML tags are not case sensitive: <B> means the same as <b>. When you surf the Web, you will notice that most tutorials use uppercase HTML tags in their examples. We always use lowercase tags. Why? If you want to prepare yourself for the next generations of HTML you should start using lowercase tags. The World

Wide Web Consortium (W3C) recommends lowercase tags in their HTML 4 recommendation, and XHTML (the next generation HTML) demands lowercase tags. Tag Attributes Tags can have attributes. Attributes can provide additional information about the HTML elements on your page. This tag defines the body element of your HTML page: <body>. With an added bgcolor attribute, you can tell the browser that the background color of your page should be red, like this: <body bgcolor="red">. This tag defines an HTML table: <table>. With an added border attribute, you can tell the browser that the table should have no borders: <table border="0"> Attributes always come in name/value pairs like this: name="value". Attributes are always added to the start tag of an HTML element. Quote Styles, "red" or 'red'? Attribute values should always be enclosed in quotes. Double style quotes are the most common, but single style quotes are also allowed. In some rare situations, like when the attribute value itself contains quotes, it is necessary to use single quotes: name='John "ShotGun" Nelson' Headings Headings are defined with the <h1> to <h6> tags. <h1> defines the largest heading. <h6> defines the smallest heading. <h1>This is a heading</h1> <h2>This is a heading</h2> <h3>This is a heading</h3> <h4>This is a heading</h4> <h5>This is a heading</h5> <h6>This is a heading</h6> HTML automatically adds an extra blank line before and after a heading. Paragraphs Paragraphs are defined with the <p> tag. <p>This is a paragraph</p> <p>This is another paragraph</p> HTML automatically adds an extra blank line before and after a paragraph. Line Breaks The <br> tag is used when you want to end a line, but don't want to start a new paragraph. The <br> tag forces a line break wherever you place it. <p>This <br> is a para<br>graph with line breaks</p> The <br> tag is an empty tag. It has no closing tag. Comments in HTML The comment tag is used to insert a comment in the HTML source code. The browser will ignore a comment. You can use comments to explain your code, which can help you when you edit the source code at a later date. <!-- This is a comment --> Note that you need an exclamation point after the opening bracket, but not before the closing bracket.

Example 2: This example demonstrates the use of line breaks in an HTML document

<html> <body> <p> To break<br>lines<br>in a<br>paragraph,<br>use the br tag. </p> </body> </html>

Example 3: This example demonstrates how you can format text in an HTML document. <html> <body> <b>This text is bold</b> <br> <strong> This text is strong </strong> <br> <big> This text is big </big> <br> <em> This text is emphasized </em> <br> <i> This text is italic </i> <br> <small> This text is small </small> <br> This text contains _subscript <br>

This text contains ^superscript </body> </html>

How to View HTML Source To view HTML source, simply click on the VIEW option in your browsers toolbar and select SOURCE or PAGE SOURCE. This will open a window that shows you the actual HTML of the page. Text Formatting Tags Tag <b> <big> <em> <i> <small> <strong> <sub> <sup> <ins> <del> 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

Citations, Quotations, and Definition Tags Tag <abbr> <acronym> <address> <bdo> <blockquote> <q> <cite> <dfn> Description Defines an abbreviation Defines an acronym Defines an address element Defines the text direction Defines a long quotation Defines a short quotation Defines a citation Defines a definition term

Character Entities Some characters have a special meaning in HTML, like the less than sign (<) that defines the start of an HTML tag. If we want the browser to actually display these characters we must insert character entities in the HTML source. A character entity has three parts: an ampersand (&), an entity name or a # and an entity number, and finally a semicolon (;). To display a less than sign in an HTML document we must write: < or < The advantage of using a name instead of a number is that a name is easier to remember. The disadvantage is that not all browsers support the newest entity names, while the support for entity numbers is very good in almost all browsers.

Example 4: This example lets you experiment with character entities. <html> <body> <p>This is a character entity: �</p> <p> Try to substitute the 000 in the edit window with a number (like 169), and press the "Edit the text and click me" button to view the result. </p>

</body> </html> Non-breaking Space The most common character entity in HTML is the non-breaking space. Normally HTML will truncate spaces in your text. If you write 10 spaces in your text HTML will remove 9 of them. To add spaces to your text, use the & nbsp; character entity. The Anchor Tag and the Href Attribute HTML uses the <a> (anchor) tag to create a link to another document. An anchor can point to any resource on the Web: an HTML page, an image, a sound file, a movie, etc. The syntax of creating an anchor: <a href="url">Text to be displayed</a> The <a> tag is used to create an anchor to link from, the href attribute is used to address the document to link to, and the words between the open and close of the anchor tag will be displayed as a hyperlink. This anchor defines a link to Yahoo.com: <a href="http://www.yahoo.com/">yahoo</a> The line above will look like this in a browser: yahoo The Target Attribute With the target attribute, you can define where the linked document will be opened. The line below will open the document in a new browser window: <a href="http://www.nitttrchd.ac.in/" target="_blank">Visit NITTTR!</a>

The Anchor Tag and the Name Attribute

The name attribute is used to create a named anchor. When using named anchors we can create links that can jump directly into a specific section on a page, instead of letting the user scroll around to find what he/she is looking for. Below is the syntax of a named anchor: <a name="label">Text to be displayed</a> The name attribute is used to create a named anchor. The name of the anchor can be any text you care to use. The line below defines a named anchor: <a name="tips">Useful Tips Section</a> You should notice that a named anchor is not displayed in a special way. To link directly to the "tips" section, add a # sign and the name of the anchor to the end of a URL, like this: <a href="http://www.nitttrchd.ac.in/html_links.asp#tips"> Jump to the Useful Tips Section</a>

A hyperlink to the Useful Tips Section from WITHIN the file "html_links.asp" will look like this: <a href="#tips">Jump to the Useful Tips Section</a> Example 5: This example demonstrates how to link to another page by opening a new window, so that the visitor does not have to leave your Web site. <html> <body> <a href="lastpage.htm" target="_blank">Last Page</a> <p> If you set the target attribute of a link to "_blank", the link will open in a new window. </p> </body> </html>

HTML Frames 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:   The web developer must keep track of more HTML documents It is difficult to print the entire page

The Frameset Tag   The <frameset> tag defines how to divide the window into frames Each frameset defines a set of rows or columns



The values of the rows/columns indicate the amount of screen area each row/column will occupy

The Frame Tag  The <frame> tag defines what HTML document to put into each frame

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 HTML document "frame_a.htm" is put into the first column, and the HTML 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> Example 6: This example demonstrates how to make a vertical frameset with three different documents. <html> <frameset cols="25%,50%,25%"> <frame src="tryhtml_frame_a.htm"> <frame src="tryhtml_frame_b.htm"> <frame src="tryhtml_frame_c.htm"> </frameset> </html

Example 7: This example demonstrates how to make a horizontal frameset with three different documents. <html> <frameset rows="25%,50%,25%"> <frame src="tryhtml_frame_a.htm"> <frame src="tryhtml_frame_b.htm"> <frame src="tryhtml_frame_c.htm"> </frameset> </html> Example 8: This example demonstrates the noresize attribute. The frames are not resizable. Move the mouse over the borders between the frames and notice that you can not move the borders. <html> <frameset rows="50%,50%"> <frame noresize="noresize" src="tryhtml_frame_a.htm"> <frameset cols="25%,75%"> <frame noresize="noresize" src="tryhtml_frame_b.htm">

<frame noresize="noresize" src="tryhtml_frame_c.htm"> </frameset> </frameset> </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). The letters td stands for "table data," which is the content of a data cell. A data cell can contain text, images, lists, paragraphs, forms, horizontal rules, tables, etc. <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 it looks in a browser: row 1, cell 1 row 1, cell 2 row 2, cell 1 row 2, cell 2

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

Headings in a Table Headings in a table are defined with the <th> tag. <table border="1"> <tr> <th>Heading</th> <th>Another Heading</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 it looks in a browser: Heading Another Heading row 1, cell 1 row 1, cell 2 row 2, cell 1 row 2, cell 2

Empty Cells in a Table Table cells with no content are not displayed very well in most browsers. <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></td> </tr> </table> How it looks in a browser: row 1, cell 1 row 1, cell 2 row 2, cell 1 Note that the borders around the empty table cell are missing. To avoid this, add a non-breaking space ( ) to empty data cells, to make the borders visible: <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> </td> </tr> </table> How it looks in a browser: row 1, cell 1 row 1, cell 2 row 2, cell 1 Example 9: This example demonstrates a table with no borders. html> <body> <h4>This table has no borders:</h4> <table> <tr>

<td>100</td> <td>200</td> <td>300</td> </tr> <tr> <td>400</td> <td>500</td> <td>600</td> </tr> </table> <h4>And this table has no borders:</h4> <table border="0"> <tr> <td>100</td> <td>200</td> <td>300</td> </tr> <tr> <td>400</td> <td>500</td> <td>600</td> </tr> </table> </body> </html>

Example 10: This example demonstrates how to add a background to a table <html> <body> <h4>A background color:</h4> <table border="1" bgcolor="red"> <tr> <td>First</td> <td>Row</td> </tr> <tr> <td>Second</td> <td>Row</td> </tr> </table> <h4>A background image:</h4> <table border="1" background="bgdesert.jpg"> <tr> <td>First</td> <td>Row</td> </tr> <tr> <td>Second</td> <td>Row</td> </tr> </table>

</body> </html>

Unordered Lists An unordered list is a list of items. The list items are marked with bullets (typically small black circles). An unordered list starts with the <ul> tag. Each list item starts with the <li> tag. <ul> <li>Coffee</li> <li>Milk</li> </ul> Here is how it looks in a browser:   Coffee Milk

Inside a list item you can put paragraphs, line breaks, images, links, other lists, etc. Ordered Lists An ordered list is also a list of items. The list items are marked with numbers. An ordered list starts with the <ol> tag. Each list item starts with the <li> tag. <ol> <li>Coffee</li> <li>Milk</li> </ol> Here is how it looks in a browser: 1. 2. Coffee Milk

Inside a list item you can put paragraphs, line breaks, images, links, other lists, etc. Definition Lists A definition list is not a list of items. This is a list of terms and explanation of the terms. A definition list starts with the <dl> tag. Each definition-list term starts with the <dt> tag. Each definition-list definition starts with the <dd> tag. <dl> <dt>Coffee</dt> <dd>Black hot drink</dd> <dt>Milk</dt> <dd>White cold drink</dd> </dl> Here is how it looks in a browser: Coffee Black hot drink Milk White cold drink

Inside a definition-list definition (the <dd> tag) you can put paragraphs, line breaks, images, links, other lists, etc. Example 11: <html> <body> <h4>A nested List:</h4> <ul> <li>Coffee</li> <li>Tea <ul> <li>Black tea</li> <li>Green tea</li> </ul> </li> <li>Milk</li> </ul> </body> </html> The output of the above code will be: A nested List:   Coffee Tea o o  Milk Black tea Green tea

Forms A form is an area that can contain form elements. Form elements are elements that allow the user to enter information (like text fields, textarea fields, drop-down menus, radio buttons, checkboxes, etc.) in a form. A form is defined with the <form> tag.

<form> <input> <input> </form>

Input The most used form tag is the <input> tag. The type of input is specified with the type attribute. The most commonly used input types are explained below. Text Fields Text fields are used when you want the user to type letters, numbers, etc. in a form. <form> First name: <input type="text" name="firstname"> <br>

Last name: <input type="text" name="lastname"> </form> How it looks in a browser: First name: Last name: Note that the form itself is not visible. Also note that in most browsers, the width of the text field is 20 characters by default. Radio Buttons Radio Buttons are used when you want the user to select 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 it looks in a browser: Male Female Note that only one option can be chosen. Checkboxes Checkboxes are used when you want the user to select one or more options of a limited number of choices. <form> <input type="checkbox" name="bike"> I have a bike <br> <input type="checkbox" name="car"> I have a car </form> How it looks in a browser: I have a bike I have a car The Form's Action Attribute and the Submit Button When the user clicks on the "Submit" button, the content of the form is sent to another file. The form's action attribute defines the name of the file to send the content to. 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 it looks in a browser:
Submit

Username:

If you type some characters in the text field above, and click the "Submit" button, you will send your input to a page called "html_form_action.asp". That page will show you the received input. Example 12: This example demonstrates how to create text fields on a HTML page. A user can write text in a text field. <html> <body> <form> First name: <input type="text" name="firstname"> <br> Last name: <input type="text" name="lastname"> </form> </body> </html>

Example 13: This example demonstrates how to create a password field on a HTML page <html> <body> <form> Username: <input type="text" name="user"> <br> Password: <input type="password" name="password"> </form> <p> Note that when you type characters in a password field, the browser displays asterisks or bullets instead of the characters. </p> </body> </html>

The Image 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 it 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 on your page. The syntax of defining an image: <img src="url"> The URL points to the location where the image is stored. An image named "boat.gif" located in the directory "images" on "www.w3schools.com" has the URL: http://www.w3schools.com/images/boat.gif. The browser puts the image where the image 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. The Alt Attribute The alt attribute is used to define an "alternate text" for an image. The value of the alt attribute is an author-defined text: <img src="boat.gif" alt="Big Boat"> The "alt" attribute tells the reader what he or she is missing on a page if the browser can't load images. The browser will then display the alternate text instead of the image. It is a good practice to include the "alt" attribute for each image on a page, to improve the display and usefulness of your document for people who have text-only browsers. Example 14: This example demonstrates how to align an image within the text. <html> <body> <p> An image <img src="hackanm.gif" align="bottom" width="48" height="48"> in the text </p> <p> An image <img src ="hackanm.gif" align="middle" width="48" height="48"> in the text </p> <p> An image <img src ="hackanm.gif" align="top" width="48" height="48"> in the text </p> <p>Note that bottom alignment is the default alignment</p> <p> An image <img src ="hackanm.gif" width="48" height="48"> in the text </p> <p> <img src ="hackanm.gif"

width="48" height="48"> An image before the text </p> <p> An image after the text <img src ="hackanm.gif" width="48" height="48"> </p> </body> </html>

Example 15: This example demonstrates how to let an image float to the left or right of a paragraph. <html> <body> <p> <img src ="hackanm.gif" align ="left" width="48" height="48"> A paragraph with an image. The align attribute of the image is set to "left". The image will float to the left of this text. </p> <p> <img src ="hackanm.gif" align ="right" width="48" height="48"> A paragraph with an image. The align attribute of the image is set to "right". The image will float to the right of this text. </p> </body> </html> Example 16: This example demonstrates how to adjust images to different sizes. <html> <body> <p> <img src="hackanm.gif" width="20" height="20"> </p> <p> <img src="hackanm.gif" width="45" height="45"> </p> <p> <img src="hackanm.gif" width="70" height="70"> </p> <p> You can make a picture larger or smaller changing the values in the "height" and "width" attributes of the img tag. </p> </body> </html>