Among the billions of videos seen on YouTube since its launch a decade ago, these have been the most popular:
"Gangnam Style," the music video by South Korea's Psy - accompanied by a horse-riding-like dance that became a global sensation - has been viewed more than 2.3 billion times.
Justin Bieber's "Baby" music video with rapper Ludacris, viewed 1.15 billion times.
Katy Perry's "Dark Horse" music video with Juicy J, 917 million views.
Katy Perry's "Roar," 889 million views.
"Party Rock Anthem" by the electronic dance music group LMFAO, 856 million views.