The new method rewards high-interest content, old and new.
Edgerank was based on these three elements: affinity, weight, and time decay.
The new algorithm ditches the time decay aspect and focuses on interactions. If an older post gets sufficient new comments, it will re-appear atop people’s news feeds.
The News Feed Algorithm responds to signals from users, including:
Early data suggest the new algorithm is increasing interaction rates. Most people just scan their News Feeds, missing relevant posts. When those posts are re-introduced to the News Feed, users have another opportunity to respond to them.