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How does a Web browser work?

When your Web browser reads a document, the hyperlinks to other Web pages or Web sites appear as text highlighted in another color or as a graphic. When you click on the highlighted text or the graphic with your mouse, you are transported to that site (in reality, the data from the site is transported to you, not vice versa). You never see the code. It merely acts as an instruction to your Web browser to go to another location on the Web.

What actually happens

Hyperlinks are included in the Web document, as a computer code called HTML (Hyperlink Text Markup Language). HTML uses Berners-Lee's HTTP (Hyper Text Transfer Protocol) and allows the Web site operator to include cross-references to other documents within the site, and from there, to other sites or documents within those sites. Using something called "Metatext" the Web site operator or designer can also insert keywords to help search engines locate your site when someone is searching for information you provide at the site.

An Internet address is called a URL (Universal Resource Locator - pronounced "U-R-L") - they are more commonly called "domain names." Each part of the URL means something different, and is separated by dots from the other parts of the URL.

When you type a URL into your browser it breaks the URL into three parts: protocol (http), server name (www.awebsite.com) and file name (index.html).

The protocol part simply refers to and identifies a Web transmission. The first part of an URL is the "scheme." It tells you where on the Internet the information you are seeking is located. (Remember that there's more to the Internet than the Web.) The most common scheme, since the development of the Web is HTTP. The letters "http" in the URL tell you that it's a Web address (because it uses HTTP, Berner-Lee's protocol).

Communicating with a name server, the browser translates the server name into an IP (Internet Protocol) address (the code a machine uses to recognize domain names - we only see them written in words to make it easy for users but you can type the IP address of a Web site - if you know it - into your browser and it will still take you there) so that it can connect to that server machine on port 80 (the standard port for web traffic).

All domain names have to use a suffix (or zone), depending upon the type of organization or entity involved. The ".com" indicates a commercial organization site, rather than an Internet network (.net), international organization (.int), a higher educational institution (.edu), a not-for-profit organization (.org), military (.mil) or government (.gov) site. Given the high demand for domain names, additional zones are being added to identify the type of commercial site, such as ."law", ".med, and ."biz". These are not yet available, however.

Once connected, the browser sends what is termed a GET request for the file name specified in the URL (in other words, it asks the server to send the information). The server sends the file's HTML to the browser, the browser reads the HTML tags and translates them to what appears on your monitor. So your browser works very hard to deliver you information - you just don't see it.

Curently, the most popular Web browser is Microsoft's Internet Explorer but there are many to choose from:

• Internet Explorer
• Firefox
• NeoPlanet
• Netscape
• Opera :: Opera for mobile
• Safari (MAC)

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