TED is a nonprofit devoted to Ideas Worth Spreading. It started out, in 1984, as a conference bringing together people from three worlds: Technology, Entertainment, Design. Talks are usually short, 10 to 20 minutes or less, and most are supported by short videos or slides projected behind the speaker. Think show-and-tell by and for adults.
Subjects range from the challenges providing solar-powered LED lightbulbs to Haitians (economics, cultural differences) to Hurdy-gurdy for beginners (music, history) to why a YouTube video goes viral (math, social studies).
TEDx are independent TED conferences use the TED format. These talks happen all over the U.S. and the world. Many are sponsored by local school districts and allow students and faculty to share their interests, research and ideas.
These TED and TEDx talks are recorded and the best are placed on the Internet, in places like TED.com and YouTube. There are literally thousands of talks by speakers from all walks of life and all ages.