RDFa ("Resource Description Framework in attributes") is having its five minutes of fame: Google is beginning to process RDFa and Microformats as it indexes websites, using the parsed data to enhance the display of search results with "rich snippets." Yahoo!, meanwhile, has been processing RDFa for about a year. With these two giants of search on the same trajectory, a new kind of web is closer than ever before.

The web is designed to be consumed by humans, and much of the rich, useful information our websites contain, is inaccessible to machines. People can cope with all sorts of variations in layout, spelling, capitalization, color, position, and so on, and still absorb the intended meaning from the page. Machines, on the other hand, need some help.

A new kind of web—a semantic web—would be made up of information marked up in such a way that software can also easily understand it. Before considering how we might achieve such a web, let's look at what we might be able to do with it.