Facebook is celebrating its fifth anniversary today and reports 150 million users all over the world.

The website's creator Mark Zuckerberg says many people now use the site efficiently share information, with it evolving considerably since its conception in 2004.

"Enabling efficient sharing is important because it makes the world more open, and this gives everyone a voice to express ideas and initiate change," he continues.

Mr Zuckerberg adds that the website will continue to change to meet the needs of its users, offering a "safe and trusted environment for people to interact online" as the internet opens up the world.

Nielsen Online's press alert said last year that after 17 successive monthly increases in UK audience since July 2006, Facebook suffered its first ever drop.

Its traffic fell five per cent from 8.9 million unique visitors in the UK in December 2007 to 8.5 million in January 2008.

According to a recent survey by Connect, the two biggest IT headaches for businesses were 'everyday hassles with IT' (37 per cent) and 'security concerns' (32 per cent).