These three paragraphs are unformatted, monospacedMonospaced text is text in which all characters, whether narrow such as an “I” or wide like an “M,” are given the same amount of horizontal space—similar to an old typewriter. text. For years, this format (called "plain text" or ASCIIAmerican Standard Code for Information Interchange (pronounced: ass-kee). text) has been the stuff of which communication on the Internet was made. This is because plain text is the lowest common denominator -- plain text documents can be opened and read by virtually any computer on any system.

This text-only world has changed dramatically. The World Wide Web and the browsers designed to navigate it have transformed the Internet into a multi-media environment -- one in which anyone can publish his or her own documents containing not only text of various sizes, styles, and colors but images, sounds, movies, games and more.

Although web pages seldom appear onscreen as ASCII text, it remains the basic material from which all web pages are constructed. Transforming plain text into web pages is done by "marking it up" with small instructions, called "tags" that tell the browser app how to display it on screen.