What on earth is going on at NaNoWriMo HQ? Here's a high level summary compiled by an anonymous community member.
Prompt
A prompt (also writing prompt) is a short entry that generally contains a question or idea to help you pick a topic to write about. They can be silly, serious, or anywhere in between. Writing prompts are often used in the Word Wars, Prompts, & Sprints forum, word wars, and @NaNoWordSprints. The adoptables can also be used as prompts.
An example of a prompt would be: If you could travel to any place, real or fictional, from any time, what would it be and why?
Prompt generators exist all over the web. The Plot Machine is a prompt generator that appeared on the Script Frenzy website.
See also Dare, a prompt that tends to be on the silly side.