What exactly is Web 2.0?

[braketech]

Web 2.0 is a concept, of improving user interaction online.

[GladysTap]

Web 2.0 describes World Wide Web sites that emphasize user-generated content, usability, and interoperability. The term was popularized by Tim O'Reilly and Dale Dougherty at the O'Reilly Media Web 2.0 Conference in late 2004, though it was coined by Darcy DiNucci in 1999.