NaNoWriMo stands for National Novel Writing Month, and it is an event held annually during the month of November. Basically the idea is to write every day for 30 days with a goal of hitting 50,000 words (or potentially more). And just about every writer on the planet has heard of it or volunteered for the challenge.
To be fair, I have yet to finish NaNoWriMo (something I hope to change this year). I attempted NaNoWriMo back in 2009, but I had to stop as the pressure of finishing my Bachelor's degree became too much. I made the decision to graduate (which I don't regret), but I did write about 37K words before I stopped. I consider that to be a decent attempt and I learned just how much I could accomplish in such a relatively short time.
Since November is usually a cold month (here in the U.S. anyway), there's a great reason to huddle inside with your writing implements, frantically getting those words down every day. And NaNoWriMo means not having to write perfectly - just write. Sure you'll have to go back later and edit, but that's a given no matter how you choose to write. Just make sure you write.
What will you be doing this November?