YouTube

is a video-sharing website where users can upload videos. It is currently (7/2012) the largest such site, and was founded in 2005 by  Chad Hurley, Steve Chen, and Jawed Karim, who all worked at PayPal before. While it mainly featured movies from regular folks (and some illegal user uploads) at the beginning, but eventually YouTube grabbed enough market share to attract higher quality content over the years. Now, there is something for everyone, and YouTube continues to push for high-quality content, while keeping the support from amateur video-makers. The company was acquired by Google in 2006 for $1.6B.