Newbie question: Web 2.0

Maybe it;s just the terminology, but I don't get what web 2.0 means in the context of IM/SEO. For example, when a someone writes 'If i create ~30 Web 20s and post an article per keyword on each of them.' in a post, what actually does that mean. What does he create and where does he post the article? Other sites, other peoples blogs???

web 2.0 is the term for wp, tumblr, weeble and so on.
the term come out after the first internet stock excange crash.

so there will be articles on free websites like the mentioned

when someone writes 'If i create ~30 Web 20s and post an article per keyword on each of them.'

Click to expand...

What he means that he would write articles and submit them to sites like Squidoo, Tumblr, Wordpress etc.
A list of web 2.0's:

http://www.web20searchengine.com/web20/web-2.0-list.htm