Facebook smashed investors' expectations with a 52% jump in quarterly revenue as it sold more ads targeted at a fast-growing number of mobile users, sending its shares sharply higher after hours.
The world's biggest online social network bucked the trend of underwhelming tech results from Apple and eBay.
The strong results came in the face of economic uncertainty around the world and a strong US dollar depressing the value of overseas sales.
Facebook's dominance in mobile advertising helped to allay Wall Street concerns over its heavy investments in messaging service WhatsApp and virtual reality unit Oculus, which have not yet generated profits.
Facebook shares rose almost 12% in after-hours trading on Wall Street.
They were helped by Chief Financial Officer David Wehner's comment on a call with analysts that he expected operating expenses to increase by 30-40% over the course of theyear, a slower pace than last year.
Total revenue rose to $5.84 billion from $3.85 billion a year earlier, with ad revenue increasing 56.8% to $5.64 billion in the Christmas shopping period, when spending on advertising typically spikes.
Excluding some items, the company earned 79 cents per share.
Analysts on average had expected earnings of 68 cents per share and revenue of $5.37 billion, according to Thomson Reuters.
Apart from focusing on mobile, Facebook has been ramping up spending on what it calls "big bets," including virtual reality, artificial intelligence and drones to connect the remotest parts of the world to the Internet.
The company's chief executive Mark Zuckerberg, who returned from two months of paternity leave this week, has said virtual reality represents the next major computing platform.
In January, Facebook began taking orders for a consumer version of the Oculus Rift, a head-mounted virtual reality unit.
The company has also begun monetising some of its other units, such as photo-sharing app Instagram, which surpassed 400 million users last year and began selling ads in September.
Facebook said mobile ads accounted for 80% of total ad revenue in the quarter, compared with about 78% in the third quarter and 69% a year earlier.
Facebook's service is not available for users in China but it can still sell ads to companies there.
The company, which has the world's most popular smartphone app, has also been benefiting from a surge in video views that has attracted advertising dollars.
Facebook said it had 1.59 billion monthly active users as of December 31, up 14% from the end of 2014. Of those, 1.44 billion used the service on mobile devices, an increase of 21%.
Analysts had expected the company to report 1.58 billion monthly active users, with 1.43 billion accessing the service through smartphones and tablets, according to market research firm FactSet Street Account.
Up to last night's close at $94.45, Facebook's stock had risen nearly 25% in the past 12 months.
