It began with three friends searching for an easier way to share videos. One - Jawed Karim - uploaded the site's first clip - a movie of himself dressed in an anorak at San Diego Zoo.

By the end of its first year YouTube was broadcasting 25 million videos a day and it was soon bought by the internet giant Google. In 2010 24 hours of video are now uploaded every minute.

The site's also become an important political tool - almost a million people watched a wounded girl dying during protests in Iran in July 2009. President Barack Obama successfully used the site during his election campaign.

Thousands of teenagers around the world have also used the site to upload embarrassing videos of friends and its creators have been forced to deny claims that it's encouraged bullying.

With online habits and fads constantly changing no-one's sure what the next five years hold for YouTube. Some believe it could end up as a TV channel beamed into our living rooms. Others predict it will be overtaken by new technology and dumped on the internet scrap heap.

Maddy Savage, BBC News

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Vocabulary

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anorak

coat that protects the wearer against rainy weather

wounded

injured

deny

in this case, to say that something is not true

bullying

hurting or intimidating someone less powerful

fads

activities or items which are very popular for a brief period of time

end up

to eventually become something

beamed

sent out as an electronic or radio signal

overtaken

replaced or surpassed

dumped

abandoned

scrap heap

a pile of discarded metal or rubbish