From NaNoWriMo website:
National Novel Writing Month happens every November! It’s a fun, seat-of-your-pants writing event where the challenge is to complete an entire novel in just 30 days. For one month, you get to lock away your inner editor, let your imagination take over, and just create!
That means participants begin writing November 1 and must finish by midnight, November 30. The word-count goal for our adult program is 50,000 words, but the Young Writers Program (YWP) allows 17-and-under participants to set reasonable, yet challenging, individual word-count goals.
In 2013, over 300,000 adults participated through our main site, and nearly 90,000 young writers participated through the YWP.
Click here for more information about the NaNoWriMo Young Writers Program.