What is Web 2.0?

Web 2.0 is a term  that was introduced in 2004 to describe a new generation of Web applications which provides dynamic user participation, social interaction and collaboration.  In a nutshell, the next step of the www.

In an article written in 2005, Tim O'Reilly lists on O'reillyNet a sampling of an initial brainstorming of applications that are Web 1.0 vs. Web 2.0 at that time:

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