According to Strategy Analytics’ latest research, the number of Internet users around the world that use social networks such as Facebook, MySpace and Twitter will reach 900 million by the end of this year and increase to 1.85 Billion by the end of 2015. However, the Strategy Analytics report, “Global Social Network Market Forecast,” finds that there are already significant regional differences in the adoption of different social networks, as well as in business models for how social networks are monetized.

Less than 40% of Internet users in Asia were regular social network users at the end of 2009 compared to approximately 60% in North America and Western Europe. As the Asian Internet market continues to grow at breakneck speed, Strategy Analytics projects that this region will represent the greatest growth opportunity for social networks over the next five years.

“Facebook has conquered most places in the Western World but has struggled to gain traction in many Asian markets,” said Martin Olausson, Director of Digital Media Research at Strategy Analytics. “We believe that Facebook needs to increase its focus and commitment to the important and rapidly growing Asian market if it wants to remain the world’s leading social network five years from now.”

There are also different revenue models for monetizing social networks emerging in different regions. Whereas revenues from sales of virtual items are estimated to only represent 9% of total social network revenues in North America this year, they are expected to represent nearly 22% of revenues in the Asian market.

“While advertising has been and will continue to be the main revenue source for most social networks, revenues from selling virtual items and social network credits will ramp up rapidly in some regions,” said Jia Wu, Analyst at Strategy Analytics’ Digital Consumer Practice and author of the report. “Social networks, such as Tencent and Cyworld in Asia, already generate significant revenues by selling avatar accessories and virtual gifts. Based on their successful experience, we expect to see other markets to adopt this business model for gaining incremental revenues going forward.”