Web 2.0

• What Is Web 2.0: Design Patterns and Business Models for the Next Generation of Software by Tim O'Reilly
• Web 2.0, article from Wikipedia

What it isn't

Buzzword or something "real"?

• No formal definition (say like XHTML 1.0 or XHTML 2.0)
• Web 2.0 does have characteristics and features
• There are some technologies commonly found in "Web 2.0"