From the site:
"What is reddit?
A source for what's new and popular on the web -- personalized for you. We want to democratize the traditional model by giving editorial control to the people who use the site, not those who run it. Your votes train a filter, so let reddit know what you liked and disliked, because you'll begin to be recommended links filtered to your tastes. All of the content on reddit is from users who are rewarded for good submissions (and punished for bad ones) by their peers; you decide what appears on your front page and which submissions rise to fame or fall into obscurity."