Netflix knows what you want to watch next. And it’s starting in 4, 3, 2, 1 seconds…. They these recommendations automatically using a recommendation algorithm. This algorithm instructs Netflix’s servers to process information from its databases to determine which movies a customer is likely to enjoy.

The algorithm takes into account:

  • The films themselves, which are arranged as groups of common movies
  • The customers’ ratings, rented movies and current queue
  • The combined ratings of all Netflix users

The first algorithm behind these recommendation was called CineMatch. The CineMatch algorithm had a long run and proved fairly successful at predicting movies that subscribers would like. According to Netflix, these predictions were accurate within half a star 75 percent of the time, and half of Netflix users who rented CineMatch-recommended movies gave them a five-star rating.

Source: How stuff works