First, computer programs that display Web pages are called Web browsers, and there are several different Web browsers with varying sets of features, levels of performance, availability for different types of computers--Windows, Macintosh, Linux--and compliance with different sets of standards.

The oversight body for worldwide standards for Web servers and browsers is the World Wide Web Consortium (W3C); its primary goal is to make the "universe of network-accessible information...available to all people, whatever their hardware, software, network infrastructure, native language, culture, geographical location, or physical or mental abililty." Effectively, there are now two sets of standards--essentially those used by Microsoft and those used by everyone else. Microsoft Web technology generally follows W3C standards, but then adds its own proprietary standards that only its browser and Web server understand. Most of the other developers of browsers and servers make them highly W3C-compliant and do not promote proprietary standards.