TED is a nonprofit devoted to Ideas Worth Spreading. It started out (in 1984) as a conference bringing together people from 3 worlds: Technology, Entertainment, Design. Since then its scope has become ever broader.
TED is owned by The Sapling Foundation, a private nonprofit foundation, a 501(c)3 organization under US tax code. It was established in 1996 by Chris Anderson, who was at that time a magazine publishing entrepreneur.
Along with 2 annual conferences, the TED Conference in Long Beach and Palm Springs each spring, and the TEDGlobal conference in Edinburgh UK each summer, TED includes the award-winning TEDTalks video site, the Open Translation Project and TED Conversations, the inspiring TED Fellows and TEDx programs, and the annual TED Prize.
Since June 2006, the talks have been offered for free viewing online, under a Creative Commons license, through TED.com. As of November 2011, over 1,050 talks are available free online. By January 2009 they had been viewed 50 million times. In June 2011, the viewing figure stood at more than 500 million.
TED's official app offer more than 900 TEDTalk videos (with more added each week) for both iPad and iPhone.
For who is not familiar with english language in the AppStore there is an unofficial app TEDiSUB. Thanks to it, you can enjoy TED Talk videos with subtitles.
Video tutorial and previews of the app: