3. Interactive information sharing,

4. Interoperability,

5. User-centered design and

6. Collaboration on the World Wide Web.

8. Web-based communities

9. Hosted services, web applications

10. Social-networking sites

11. Video-sharing sites

12. Wikis

13. Blogs, Mashups, and Folksonomies.

15. Users can build on the interactive facilities of "Web 1.0" to provide "Network as platform" computing.

16. Users can own the data on a Web 2.0 site and exercise control over that data.

18. Other characteristics, such as openness, freedom and collective intelligence by way of user participation, can also be viewed as essential attributes of Web 2.0.

20. Links

21. Authoring

22. Tags

23. Extensions

24. Signals

26. Some of those sites are listed below

27. For Photos :: Flickr ( www.flickr.com )

28. For Video :: Vimeo (www.vimeo.com)

30. Del.icio.us (del.icio.us)

31. Digg ( www.digg.com )

32. For Newsreaders / RSS:: Bloglines( www.bloglines.com )

33. Collaboration / Word Processing::

34. Writeboard ( www.writeboard.com )

36. Local Directories :: Google Local ( www.google.com/local )

37. Chat/IM :: Meebo ( www.meebo.com )

39. E-learning 2.0

40. Government 2.0

41. Health 2.0

42. Library 2.0

44. Many of the ideas of Web 2.0 had already been featured in implementations on networked systems

46. But perhaps the most common criticism is that the term is unclear or simply a buzzword.

47. "Nobody really knows what it means...If Web 2.0 for you is blogs and wikis, then that is people to people. But that was what the Web was supposed to be all along."