The Web

The Web is a vast collection of documents on the Internet that are linked together via hyperlinks. The Internet consists of millions of computers worldwide that communicate electronically. A hyperlink is a predefined link between two documents. The hyperlinks allow a user to access documents on various Web servers without concern for where they are located. A Web server is a computer on the Internet that serves out Web pages on request. From a document on a Web server in California, the user is just one mouse click away from a document that is stored, perhaps, on a Web server in France. Hyperlinks are integral to the Web. Without them, there would be no Web.

Users gain access to the Web through a browser. A browser is a computer program that lets users browse or "surf" the Web by fetching documents from Web servers and displaying them to the user. To move from one document to another, the user clicks a highlighted (often underlined) word or image that represents a hyperlink. The browser then retrieves the document that is at the other end of the hyperlink and displays it on the screen. For example, a user could be in a document about baroque music and click the highlighted words Johann Sebastian Bach that are linked to "Bach's home page." (On the Web, all celebrities and everyone else who wants one have a home page.) After the browser fetches Bach's home page (instantly, in the best case), it appears on the user's screen.

Development of the Web

The Web was invented around 1990 by Tim Berners-Lee with Robert Cailliau as a close ally. Both of them were then working at CERN, which is the European Laboratory for Particle Physics. Tim is a graduate of Oxford University and a long-time computer and software expert, and is now the director of the World Wide Web Consortium (W3C), an organization that coordinates the development of the Web. He also is a principal research scientist at Massachusetts Institute of Technology's Laboratory for Computer Science and Artificial Intelligence (MIT CSAIL). Robert is a 30-year veteran at CERN, where he still works. Robert organized the first Web conference in Geneva in 1993. Both Tim and Robert were awarded the ACM Software System Award in 1995 because of their work on the Web. (Robert wrote the Foreword to this book.)

Tim created the language HTML, which is used by people to exchange information on the Web. We discuss what HTML is in the next section and give a brief review of its basics later in the chapter. Tim also began work on style sheets soon afterward, but when the Web really started taking off in 1993, the work on them was not complete.

The world outside scientific laboratories discovered the Web around 1994. Since then, the Web's growth has been tremendous. Had style sheets been available on the Web from its beginning, Web-page designers would have been spared much frustration. However, releasing CSS1 two years later did offer some advantages. First, in the interim, we learned much about what visual effects Web designers want to achieve on their pages. Second, we learned that users also want their say in how documents are presented on their computer screens; for example, the visually impaired may want to make fonts bigger so that they can be read more easily. As a result, we were able to provide functionality to meet as many of these needs as possible, and even more was added when CSS2 was issued in 1998. Hence, the CSS of 1999 is a better solution than a style-sheet solution years earlier would have been.