For years, Netflix has used the standard five-star rating system for shows and movies. But according to the company's blog post, this wasn't very effective. Now the five-star system will be replaced by simple thumbs-up and thumbs-down buttons.
Netflix's recommendation system heavily relies on data used from ratings - the more people rate shows and movies, the more it learns. When many users never bother to leave ratings, it gives the recommendation system less to work with. Netflix claims that switching to thumbs (in a limited A/B test) resulted in a 200% increase in ratings activity.
In addition, the star rating seen next to each title is being replaced by a percentage. That number represents how likely you are to enjoy the content, based on your thumbs-up and thumbs-down activity.
Netflix says that the new ratings system should be live for everyone by now.