Facebook has an ingrained algorithm that monitors exactly how you engage with your friends and afterwards sorts appropriately. Resource
Friends List Order On Facebook
While the precise ranking formula is secret, it does consider the list below variables:
* Exactly how usually you see your friends' accounts
* How frequently you click on your friends' web links
* Photos/tags alike
* Common groups/ organizations
* utual Friends
* How often you look for friends
* Relative popularity (just how popular your friends are among your shared links).
So, the actual sorting is not random, but instead very carefully crafted to assist in communication as well as site involvements.
