Affinity is your relationship with users. It means that the amount a user has interacted with your Page in the past affects how likely they are to see your posts. So if they’ve clicked your links, liked or commented on your posts in the past, EdgeRank assumes they’re pretty keen to see more of your stuff, and gives it higher priority in that user’s News Feed.

Recently Facebook released an update to the News Feed algorithm called Last Actor. This update takes note of the last 50 interactions you’ve had on Facebook and gives content from those same users or Pages more prevalence in your feed. So if a user interacts with your Page in the morning, your content that afternoon or the next day will be more likely to show up in their feed (assuming they haven’t had another 50 interactions already).

Weight is how much priority EdgeRank gives to your post, based on the post type. Facebook has a hierarchy of post types, since some types garner more engagement than others. Photos and videos take top priority. Links are second, and plain text status updates are at the bottom end. Weight doesn’t end there, though.

Interaction from other users can also affect this. For instance, comments are more weighty than likes, but both affect the overall weight of the post. So a text-based status update with 50 likes and 10 comments will be more likely to show up in the Newsfeed than a photo with no engagement at all.

Time decay simply means how old is your post? The longer your post has been on Facebook, the less likely it will be to show up in a user’s News Feed. Again, this one’s not quite cut-and-dried, though. For users who only drop-in to Facebook once or twice a week, your post will be relevant for longer than it would for those users who check in twice a day.

Plus, in this month’s News Feed algorithm update, Facebook included something called Story Bumping. How this works is that if a story is relevant to the user (i.e. it comes from a user or Page they interact with often, or have interacted with recently), it will be bumped to the top of their timeline, regardless of its time decay. So relevance to the user is really the most important aspect of your content.