• January 8, 2009

Facebook has passed 150 million active users worldwide, up 10 million from just last month.

"When we first started Facebook almost five years ago, most of the people using it were college students in the United States. Today, people of all ages--grandparents, parents and children--use Facebook in more than 35 different languages and 170 countries and territories," wrote Facebook co-founder and CEO Mark Zuckerberg in a blog post Wednesday on reaching the milestone.

He also noted that if Facebook were a country, it would be the eighth most populous, ahead of Japan, Russia and Nigeria. More than 70% of Facebook users are outside the U.S. and almost half are using Facebook every day.

Facebook executives have said over the last year that the company is primarily focused on growth rather than generating revenue. But the social network may face greater pressure from investors this year to demonstrate it can monetize its vast audience.

Emarketer last month estimated Facebook's 2008 U.S. ad revenue--accounting for the vast majority of its revenue--at $210 million, up 45% from 2007. The research firm lowered its overall estimate for U.S. ad spending on social networks in 2008 to $585 million from $755 million.--Mark Walsh