14-11-2012, 02:59 PM
How Web Browsers Work
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LIKE much of the Internet, the World Wide Web operates on a client/server model. You run a web
client on your computer—called a web browser—such as Microsoft’s Internet Explorer or Firefox. That
client contacts a web server and requests information or resources. The web server locates and then sends
the information to the web browser, which displays the results.
When web browsers contact servers, they’re asking to be sent pages built with Hypertext Markup
Language (HTML). Browsers interpret those pages and display them on your computer. They also can display
applications, programs, animations, and similar material created with programming languages such as
Java and ActiveX, scripting languages such as JavaScript, and techniques such as AJAX.
Sometimes, home pages contain links to files the web browser can’t play or display, such as sound or animation
files. In that case, you need a plug-in or a helper application. You configure your web browser or
operating system to use the helper application or plug-in whenever it encounters a sound, animation, or
other type of file the browser can’t run or play.
Over the years, web browsers have become increasingly sophisticated. Browsers are now full-blown software
suites that can do everything from videoconferencing to letting you create and publish HTML pages.
Browsers now also blur the line between your local computer and the Internet—in essence, they can make
your computer and the Internet function as a single computer system.
Increasingly, a browser is not just a single piece of software, but an entire suite. The newest version of
Internet Explorer, for example, includes security features such as an anti-phishing filter. The Firefox browser
has a companion piece of email software called Thunderbird that can be downloaded as well.
When browsing the Internet, one of the most frustrating experiences is the error messages browsers display
when they’re having trouble contacting a website. Depending on which browser you use, and which
version of the browser you’re using, those messages might differ. Sometimes browsers display error messages
in plain English—but more often they don’t. The final illustration in this chapter lists the most common
browser error messages—and what they mean.