Social networking will soon become a predominantly mobile activity. The number of people accessing social networks from mobile phones will exceed 550 million in 2011, and that figure will more than triple to over 1.7 billion by the end of 2016. In other words, over two-thirds of the global user base of social networks will use smartphones and other mobile handsets to access the services.

For Facebook, the growing importance of mobile is both an opportunity and a serious strategic challenge, according to ABI Research (http://www.abiresearch.com). On one hand, mobile allows the world’s leading social network to engage with millions of new consumers, but on the other hand its ability to make money from mobile users remains untested, according to the research group.

“A huge problem for Facebook is that while on the web it is a platform, on mobile it’s just another application,” ABI Research Senior Analyst Aapo Markkanen says. “To strengthen its hand in the short term we expect Facebook to aggressively take advantage of HTML5, but in the longer term it should absolutely become a mobile operating system of its own.”

The symbiosis of social networks and mobile phones can also be seen in recent moves by Google and Apple. Google’s attempt at social networking, Google+, has been designed to benefit from deep integration with Android, which is likely to go down well with application developers. Meanwhile, Apple has teamed up with Twitter and built the microblogging service into the iOS 5.

According to ABI Research’s practice, director Dan Shey, “The interesting aspect in Apple’s and Twitter’s partnership is how it can provide iPhone users with a verifiable social identity for websites and apps. That gives developers a lot of scope to innovate in areas such as authentication, personalization and advertising. It’s a hint of things to come.”