Facebook\'s revenue doubled to $1.6 billion (Dh5.87 billion) in 2011\'s first half, a source with knowledge of its financials told Reuters, underscoring its appeal to advertisers while it grapples with intensifying competition from the likes of Google. Net income in the first half of 2011 came to almost $500 million, according to the source, who wished to remain anonymous because privately held Facebook does not disclose its results. Facebook\'s stronger results come as investors have pushed its valuation to roughly $80 billion in private markets, with many industry observers expecting the world\'s No 1 internet social network to go public next year. Its growing popularity among advertisers and its 750 million users has pressured entrenched Web companies such as Yahoo, which ousted its chief executive Carol Bartz on Tuesday. Search leader Google launched Google+, a rival social network in June that attracted more than 10 million users in its first two weeks. Google has yet to offer ads on its social network, but it is trying to increase Google+\'s appeal to consumers by offering games such as Zynga Poker and Rovio\'s Angry Birds. Facebook\'s increasing allure to marketers has helped boost the rates for its ads. The price that companies pay for every consumer that clicks on a Facebook ad increased 62 per cent between the fourth quarter of 2010 and the second quarter of 2011, according to Efficient Frontier, another firm that helps companies deliver ad campaigns on Facebook.