Web 2.0 is the current state of online technology as it compares to the early days of the Web.

The features of web 2.0 include:

1. More user interactivity and collaboration

2.Easy to connect

3. Communicate efficiently

One of the most significant differences between Web 2.0 and the traditional World Wide Web (www, retroactively referred to as Web 1.0) is greater collaboration among Internet users, content providers and enterprises. In the past, users can only view and download the data or content on the webpage. But now, users can edit or create the data to make them to be a part of the website.

The History of Web 2.0
The foundational components of Web 2.0 are the advances enabled by Ajax and other applications such as RSS and Eclipse and the user empowerment that they support.

Darcy DiNucci, an information architecture consultant, coined the term “Web 2.0 In her 1999 article, “Fragmented Future”:

“The Web we know now, which loads into a browser window in essentially static screenfuls, is only an embryo of the Web to come. The first glimmerings of Web 2.0 are beginning to appear, and we are just starting to see how that embryo might develop. The Web will be understood not as screenfuls of text and graphics but as a transport mechanism, the ether through which interactivity happens.”

Tim O’Reilly is generally credited with popularizing the term, following a conference dealing with next-generation Web concepts and issues held by O’Reilly Media and MediaLive International in 2004. O’Reilly Media has subsequently been energetic about trying to copyright “Web 2.0” and holds an annual conference of the same name.

Reference :

http://whatis.techtarget.com/definition/Web-20-or-Web-2