Web 2.0

The latest buzz words are blogs ,facebook, twitter,RSS etc. what are they?They are the tools for Web 2.0 tecnology.There are various API’s available free on net just mix them up according to your needs and develop your own mash ups. Now what are mash ups?? Say for example you want to develop an application in your facebook profile which shows various restaurants in chennai.. so you take api from google map and some info from directories and develop a mash up which you can share with your friends on your fav social networking site.
links for API’s