title: How do automated recommendation algorithms usually work?
body: <p>I just read how team BellKor’s Pragmatic Chaos is <a href="http://www.wired.com/epicenter/2009/06/winning-teams-join-to-qualify-for-1-million-netflix-prize/" rel="noreferrer">winning the Netflix Challenge</a> on Wired, and I'm curious about how this kind of algorithms usually work. I know team Bellkor's solution must be an innovative one on the field.. but how does the field usually work? Is it just a really detailed database with Markov chains being run over again and again or what? </p>