TED talk

A TED talk is a video created from a presentation at the main TED (technology, entertainment, design) conference or one of its many satellite events around the world. 

TED talks are limited to a maximum length of 18 minutes but may be on any topic. Here's the TEDx website's explanation of selection criteria: "TED looks for engaging, charismatic speakers whose talks expose new ideas that are supported by concrete evidence and are relevant to a broad, international audience."

Here's a somewhat random sample of TED talks: 

• The interspecies internet? An idea in progress
• Anatomy of a New Yorker cartoon
• Why we should build wooden skyscrapers
• The curly fry conundrum: Why social media “likes” say more than you might think
• Meet global corruption's hidden players
• How we'll resurrect the gastric brooding frog, the Tasmanian tiger
• Ingenuity and elegance in ancient African alphabets
• The dangers of "willful blindness"
• What ants teach us about the brain, cancer and the Internet
• Why we sleep

The first TED conference was in 1984; the conference has been held annually since 1990. Over the years, presenters of TED talks have included Al Gore, Bill Clinton, Bill Gates, Bono, Jane Goodall, Malcolm Gladwell, Gordon Brown, Richard Dawkins Mike Rowe, Larry Page, Sergey Brin and Vint Cerf.

TED talks are made freely available on the TED website under a Creative Commons license. 

TED curator Chris Anderson explains what makes a great TED talk great: