Called Google Buzz, the new features were rolled out to a small number of Gmail account holders on Tuesday and to the majority of users within the week. It allows users to share photos, videos, web links, conversations with "friends" - defined as pre-existing Gmail contacts. Google said it may open Buzz up to outside users in the future.
The shared information goes into a special Buzz section of Gmail and also appears on Google's profile pages. Google also launched special mobile phone apps for Buzz for Apple's iPhone and for smartphones powered by its own Android operating system.
Analysts said the move by Google was designed primarily to head off Facebook's advantage in the huge amounts of user data that it has amassed and which is highly attractive to advertisers. Gmail has 167 million users, compared to Facebook's 400 million members.
"Our belief is that organising the social information on the web - finding relevance in the noise - has become a large-scale challenge, one that Google's experience in organising information can help solve," said Buzz project manager Todd Jackson.
"There's always been a big social network underlying Gmail. Buzz brings this network to the surface by automatically setting you up to follow the people you email and chat with the most."
