An article in Explica Science discusses the scientific reasons that your dog licks you. They mention 5 specific reasons that studies have shown.
1. To show affection
It is a way of showing closeness and affection to those who live with them and to those who trust them.
2. People Taste Good
You’ve probably noticed that your dog likes licking around his food bowl or your kitchen floor after you’ve cleaned up a spill. It’s evident that he likes the taste of whatever food traces have been left behind. A human’s skin also tastes good (and salty) and dogs enjoy licking it.
3. Dogs Like to Groom Themselves and You.
In addition to corresponding to an evolutionary path, dogs lick humans and other animals in an attempt to clean them. When it cannot reach the human’s face, they may lick the closest part of the body. For this reason, it is common for them to lick people’s hands, arms or legs.
3. If you hurt yourself, he/she is trying to heal you.
A dog’s saliva contains proteins that can help clean or heal its own wounds. But there are some unique organisms in dogs that it simply is not meant to tolerate or fight. This is why, if the animal identifies that you were injured, it is possibly imitating what it would do to itself: wants to help you heal.
4. Recognition of unknown elements.
Licking is also a sensory tool especially when exploring something new. Dogs may lick a table leg to ‘check it out’.
5. Dogs are communicators
It is a way of showing closeness and affection to those who live with them and to those who trust them. Possibly to say ‘let’s play’ or “it’s almost my dinner time.”
(Source: Explica.co, Publ: December 16, 2020)