You can be proud that you have a couple of hundred fans on your Facebook page, but are they quality fans? What’s the difference really? Well, the difference is something called Edge rank. Edge rank is an algorithm that Facebook uses that determines what shows up on the newsfeed, and that includes the posts and other information from your pages.
We can all understand why everything that everyone posts on Facebook can’t possibly make it to our newsfeed, but how does Facebook go about determining what actually does show up on your feed?

EdgeRank formula
Looks complicated? Well, let’s go through it:
μe – the affinity score. How often you interact with a particular Facebook friend raises your affinity with that friend.
we – the edge weight. What interaction is going on? more weight is given to a comment than a like, for example.
de – the time delay. How long has the information been up. The longer, the less it’s worth.
So what does this all mean? Well, when all these factors are multiplied together, a high number means your object (picture, comment, tag, etc.) is more likely to show up on your Facebook friends’ newsfeed.
Taking this all into consideration, and making it simple; the people that interact with you, and you with them, are more likely to get your fresh objects in their newsfeed.
See the f8 video from April 21, 2011