According to Wikipedia, Web 2.0 is a term describing changing trends in the use of World Wide Web technology and web design that aims to enhance creativity, information sharing, and collaboration among users.
We’ve been hearing the term for a few years now, and it seemed to be an ambiguous term. On a basic level, it refers to the increase of interconnectivity and social interaction on the web. Examples of this would be Google Docs, Facebook and YouTube.
It seems that more of what we do, be it productivity or play, involves interacting on the web. When creating your website, thinking in these terms will help you keep your site relevant.