User Points is a ranking system that gives every member points based on their participation on the site. Every time a member submits, votes, or comments on an article, they will receive points. This is to promote participation and to allow other members to easily seek out those that they can communicate, share ideas, and talk with. The more participation there is on the site, the richer the content becomes. You receive points by:

Submitting Content
Voting
Commenting
Referring a Friend
Referrals Becoming Members