Evolution Web 1.0, Web 2.0 to Web 3.0

Like any other technology, the web is evolving and it is evolving rather quickly. Due to lack of standards, there seems to be a little bewilderment regarding its evolution and versions but the most acceptable stages of evolution are as follows:

• Web 1.0
• Web 2.0
• Web 3.0 (Also known as Semantic Web)

Web 1.0 – That Geocities & Hotmail era was all about read-only content and static HTML websites. People preferred navigating the web through link directories of Yahoo! and dmoz.
Web 2.0 – This is about user-generated content and the read-write web. People are consuming as well as contributing information through blogs or sites like Flickr, YouTube, Digg, etc. The line dividing a consumer and content publisher is increasingly getting blurred in the Web 2.0 era.
Web 3.0 – This will be about semantic web (or the meaning of data), personalization (e.g. iGoogle), intelligent search and behavioral advertising among other things.

Here's a video that might be help you to understand.