Facebook has launched its own search tool. Users of the world’s biggest social network will be soon able to trawl content shared among friends – providing a database of recommendations for everything from jobs to restaurant reviews. Facebook founder Mark Zuckerberg said the new system, known as “Graph Search”, is restricted to Facebook content. Graph search could increase competition with review websites like Yelp and Google Inc, according to experts. The name comes from Facebook’s growing content, data and membership, which it refers to as the “social graph”. The function is currently only available on a trial basis for a few hundred thousand of the network’s one billion plus users.