This is what's known as a nearest neighbor approach. You find people who have a history of agreement, and assume that as long as their tastes don't change very much, if they like the same things yesterday, they'll continue to like the same things today. I'm going to go into that in a lot more detail but I do want to mention that while the group lens project was going and, and it was the first 1 out there being published, 2 parallel projects were going on. One that went under various names, including Homer and Ringo, at the MIT media lab under the direction of Patty Moss. And that one grew into a product called Firefly, that did this in the domain of music and then commercially. And another one done by Belcor, Bell Communications Research, by Will Hill and others. That did it in the domain of movies. called the video recommender. All three of these started out in that same period using very similar techniques. Saying we can recommend things to people based on what other people with similar tastes seem to have already liked.