Facebook has an embedded algorithm that keeps track of just how you connect with your friends and afterwards sorts appropriately. Resource
How Facebook Friends List Order
While the exact ranking algorithm is secret, it does take into consideration the following factors:
* Exactly how commonly you see your friends' profiles
* How often you click your friends' links
* Photos/tags alike
* Typical groups/ organizations
* utual Friends
* Exactly how often you search for friends
* Family member popularity (exactly how popular your friends are amongst your shared links).
So, the actual sorting is not arbitrary, yet rather meticulously crafted to facilitate interaction and also website engagements.
