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Facebook founder Mark Zuckerberg Wednesday unveiled a box of new tools that he said will extend the social networking phenomenon to every corner of the internet.

The announcement came at a conference for Facebook developers called F8, in which Zuckerberg revealed that the world's largest social networking site has 400 million registered users. These include 100 million who use Facebook Connect, the company's online identity technology that allows users to use their profile on thousands of other websites.

Last month, Facebook surpassed Google to become the most-visited US website, and the new tools announced by Zuckerberg should help it extend that dominance.

Called Open Graph, Zuckerberg said the new technology is "the most transformative thing we've done for the web," explaining that it will allow partner sites to leverage the user's social connections to make the site more relevant to the individual and their social network.

For instance, Facebook users who visit CNN can see the stories their Facebook friends liked. If they listen to the music streaming service Pandora, the songs they like can automatically be fed to their networks, and if they use the small business review service Yelp they will be able to see what their friends think of, say, the

local sushi restaurants.

Zuckerberg said that the new system would also include a "like button" that partner sites can embed and which will allow Facebook users to rate the content. He predicted that in the first 24 hours of the technology going live the new buttons would be used over 1 billion times.