Buzz is a tab inside Gmail that provides real "newsfeed" from a user's contacts to create a social network.
Instead of finding new friends or followers like on Twitter and Facebook, Buzz provides updates from existing Gmail contacts. Users can preview photos and videos through embedded links.
At present, Facebook has over 400m users worldwide and Twitter close to 25m.
The internet search giant's move is seen as an ambitious step to conquer the social networking business.
BusinessInsider has already labelled Buzz as "late, boring and lame". Microsoft and Yahoo! have also been critical of Buzz.