Web 2.0 refers to a supposed second- generation of internet based services such as social networking sites, wikis,communication tools — that let people collaborate and share information online in ways previously unavailable.
BeforeI go into more, let me give a quick comparison between Web 2.0 and Web 1.0
Web 1.0 Web 2.0
DoubleClick --> Google AdSense
Ofoto --> Flickr
Akamai --> BitTorrent
mp3.com --> Napster
Britannica Online --> Wikipedia
personal websites --> blogging
evite --> upcoming.org and EVDB
domain name speculation --> search engine optimization
page views --> cost per click
screen scraping --> web services
publishing --> participation
content management systems --> wikis
directories (taxonomy) --> tagging ("folksonomy")
stickiness --> syndication
For info, please go to this web site
http://www.oreillynet.com/pub/a/oreilly/tim/news/2005/09/30/what-is-web-20.html
