A TED Talk is 18 minutes long

TED curator Chris Anderson explains:
“The 18-minute length works much like the way Twitter forces people to be disciplined in what they write. By forcing speakers who are used to going on for 45 minutes to bring it down to 18, you get them to really think about what they want to say. What is the key point they want to communicate? It has a clarifying effect. It brings discipline.”