San Francisco - YouTube says more than one billion people are now visiting its online video site each month to watch everything from clips of cute kittens to scenes of social unrest around the world.

The milestone marks another step in YouTube's evolution from a quirky startup launched in 2005 to one of the most influential forces in today's media landscape.

YouTube crossed the one billion threshold five months after Facebook said its online social network had reached that figure.

The vast audience has given YouTube's owner, Google, another lucrative channel for selling online ads beyond its dominant Internet search engine.

Google bought YouTube for $1.76-billion in 2006 when the video site had an estimated 50 million users worldwide. - Sapa-AP