Facebook uses machine learning in several ways:
1. Automatic friend tagging suggestions and mutual friend analysis use face recognition and clustering algorithms.
2. The newsfeed arranges posts using ML to prioritize those from close friends and favorite pages.
3. Friend suggestions are made based on mutual friend circles using ML.
4. Collaborative filtering is used for recommendations like pages, groups, events and games based on what similar users engage with.
5. Sentiment analysis of comments classifies them as positive, negative or neutral emotions to provide insight.