Facebook tops 500 million users

Chief executive Mark Zuckerberg revealed the figure on Tuesday in a posting to the company's official blog.

"This is an important milestone for all of you who have helped spread Facebook around the world," he said. "Now a lot more people have the opportunity to stay connected with the people they care about."

The announcement comes amid a time of turmoil for Facebook. The company has struggled to balance its burgeoning advertising business with user privacy concerns, and many have criticised Facebook for its handling of user data.

Other technology companies were quick to applaud Facebook's achievement, however. Salesforce credited the site with helping to shape many of its own services.

"Facebook's stunning growth is pushing the entire IT industry to think social," said Salesforce chief marketing officer Kendall Collins.

"Facebook inspired us to bring technologies like profiles, groups and real-time feeds to the enterprise with Salesforce Chatter, leading enterprise collaboration into the modern age."

Phil Stewart, customer service director at Virgin Media Business, also praised Facebook, noting that 14 per cent of UK businesses have adopted the social networking service for customer relations.

"This multi-channel approach to communications is having a huge impact on customer relations, helping firms to take part in more personal conversations with their customers," said Stewart.

He added that it is not just "digital natives" who want to engage with brands and customers online. The fastest growing demographic on Facebook is the over 35s, according to research firm Nielsen, many of whom are now connecting with colleagues, customers and business acquaintances on the site.

Facebook is launching an application called Facebook Stories to commemorate the milestone. The tool will allow users to submit and share their own stories about how they use the site to connect with others.