How Facebook works - the mystery of EdgeRank

I've realised that sometimes I talk about the intricacies of the social and anthropological drivers of social media without actually stepping back and making sure that everyone understands how the platforms themselves function. So here's a very brief explanation of how Facebook works and what it means to brands.

As I'm sure you'll all know, Facebook is social utility that allows people to create an online identity through which they can build connections to their friends, family, associates, campaigns, businesses and brands in which they're interested.

Most of the activity within Facebook happens within the News Feed. This is a constantly updating list of stories from the friends and pages that a user chooses to follow. A story is anything that happens in Facebook that creates an update - this can be a new post, comment, like, share or any action within the platform. Facebook calls these updates "Edges".

The average NZ FBer has 203 friends and follows at least one brand. That means their News Feed contains a lot of updates. So Facebook has worked out a way of making sense of these updates to ensure that a user gets the information that they would be most interested in at the top of their feed. This is called "EdgeRank".

EdgeRank orders "Edges" (or stories) according to three values - Affinity, Weight and Time Decay. It's important that brands understand how to make EdgeRank work them so that they can get into users' newsfeeds.

Affinity is how close the user is to the generator of the "Edge". Affinity is built by repeat interactions with the brand's posts - the more often they interact with brand updates through liking, commenting, sharing, clicking etc, the higher the affinity value. It's therefore important that brands only post what they think their users will be interested in. Every post that isn't of interest and therefore doesn't get engagement reduces this affinity rating.

Weight is dictated by the type of "Edge" that is created. The easiest way to think of this is that the longer it takes to create the post, the greater the weight. So a photo or video post carries more weight than a text or link post. A comment carries more weight than a "like". Don't get confused by this - it doesn't mean we should be writing essays. The length of the post is not important, it's the type that makes the difference.

Time Decay is the most self-explanatory of the EdgeRank values. This is simply how old the post is. An Edge has a fairly short lifespan, so it's important that brands only post when their audiences are likely to be active on Facebook.

It's important to understand that thanks to EdgeRank, a branded page will never reach 100% of its "likes". In fact, the proportion will often be fairly low and one of the metrics that a brand should use to track its success on Facebook is the interaction rate (number of interactions per post per thousand fans). This is a good way of tracking how much of your audience actively engages with your content and therefore whether you're posting the right content at the right time.

Here's a good infographic I've found explaining how EdgeRank could apply to different situations: