Edgerank

EdgeRank is the generic name for the algorithm Facebook uses to decide which articles to show in a particular user's news feed.

Three factors are taken into account: proximity (how close the user was to the content), weighting (what action the user took on the content, how, how it was shared, etc. content is to date).

In 2013, Facebook started using a different type of algorithm that takes into account over 100,000 factors (with three EdgeRanks).