18 of 2011's most impactful TEDTalks combined with new blog posts written by the people who delivered them, examining how their ideas were impacted by being shared with a global audience. The HuffPost blogging community was also invited to weigh in on the issues and ideas raised by the talks.

Why 18? It's a bit of an inside joke. TEDTalks are famously limited to no more than 18 minutes -- that way, no one has the chance to get bored. So 18 seemed like the perfect number for our countdown.

Each of the 18 accounts includes the video of the talk itself.

The Huffington Post, 12/1/11