With over a billion users and over a hundred hours of videos uploaded every minute - YouTube has become a global phenomenon.
It's a relatively new craze when you compare it to the TV or radio.
YouTube was founded in 2005 and was bought by internet giant Google in 2006.
Compare that to the rise of the radio, which has been around for more than a hundred years, and television - which first became popular in the 1930s - and you can see that YouTube has grown very fast.
And that success means it's also home to some of the biggest rising stars, so Nel's been to meet them and their fans.