A viral video is a video that becomes popular through a viral process of Internet sharing, typically through video sharing websites, social media and email.
Viral videos often contain humorous content and include televised comedy sketches, such as The Lonely Island's "Lazy Sunday" and "Dick in a Box", Numa Numa videos, The Evolution of Dance,Chocolate Rain on YouTube; and web-only productions such as I Got a Crush... on Obama. Some eyewitness events have also been caught on video and have "gone viral" such as the Battle at Kruger.
In 2012, the Kony 2012 video by Invisible Children, Inc. became the most viral video in history, with approximately 34,000,000 views three days after its upload to YouTube on 5 March 2012, and 100,000,000 views six days after publication. Another recent example is the 2012 single "Gangnam Style" by Psy, which received one billion views in five months and is the most viewed video on YouTube since 2012.
Videos were shared long before YouTube or even the Internet by word-of-mouth, film festivals, VHS tapes, and even to fill time gaps during the early days of cable. Perhaps the earliest was Reefer Madness, a 1936 "educational" film that circulated under several different titles. It was rediscovered by Keith Stroup, founder of NORMAL, who circulated prints of the film around college film festivals in the 1970s. The company who produced the prints, New Line Cinema, was so successful they began producing their own films. The most controversial was perhaps a clip from a newscast from Portland, Oregon in November 1970. In the clip, the disposal of a beached whale carcass by dynamite is documented, including the horrific aftermath of falling mist and chunks since the exclusion zone wasn't big enough. The exploding whale story obtained urban legend status in the Northwest and gained new interest in 1990 after Dave Barry wrote a hysterical column about the event, leading to copies being distributed over bulletin board systems—a sort of primitive Internet—around 1994.