YouTube said that the number of videos watched daily at the website has broken the two-billion mark as the service begins celebrating its fifth birthday.

"Thanks to you, our site has crossed another milestone and now exceeds over two billion views a day," YouTube team members said in a blog post.

"That's nearly double the prime-time audience of all three major US television networks combined."

The news came with the launch of a YouTube 5 Year channel devoted to the service's history and cultural influence.

The YouTube 5 Year channel features a "My YouTube Story" project compiling tales by people from around the world describing how YouTube has changed or shaped their lives.

A documentary film maker has chronicled stories ranging from an Iranian protester using YouTube to get news to the world to a man sharing a video journal of his battle with cancer.

The channel has an interactive timeline of important moments in YouTube history.

"We never could have predicted what YouTube's first five years would bring, and it's difficult to imagine what the next five will look like," the YouTube Team said.

"Five years ago in May, after months of late nights, testing and preparation, YouTube's founders launched the first beta version of YouTube.com."

San Bruno, California-based YouTube was the brainchild of then PayPal co-workers Chad Hurley, Steve Chen and Jawed Karim.

Google bought YouTube in a $1.65 billion deal about 19 months after the online video-sharing service was founded in February of 2005.

The internet giant has been carefully transforming YouTube into a money-making stage for enjoying works ranging from backyard videos to independent films.