Browser Technologies

Although Microsoft’s Internet Explorer, as shown in Figure 8-1, dominates the Windows market, there are still dozens of browsers to choose from. Because the World Wide Web is based on open standards, most browsers work in similar ways and use the same technologies. The examples and lessons in the next few chapters refer to Internet Explorer, but can be applied to many existing browser programs.

Microsoft Internet Explorer 5.5

Figure 8-1. Microsoft Internet Explorer 5.5

What Is a Browser?

A browser is a software application that requests web pages and information from a Hypertext Transfer Protocol (HTTP) server and interprets and displays the results. The information sent back from a web server contains display codes (called tags ), pictures, graphics, scripting codes, hypertext links, audio files, and all the other supported forms of web content.

Browsers work by requesting information from a web server, often initiated by the user typing in the web site’s address. A TCP/IP connection to the host is made over port number 80, which is assigned to the HTTP protocol (although any port number can be used if previously agreed upon). The web server accepts the connection. The client browser sends a GET request, which initiates the server to send back information. The response includes a stream of ASCII characters following the HTML formatting conventions and any binary components. After the response ...

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