There are many reasons that dogs lick us, and contrary to many theories, this is usually one of the most natural things for a hound to do. Why do dogs lick? The most important thing is for you to recognize the difference between happy licking, and the type which signals your dog has a problem which needs to be addressed.

Dogs may lick due to behavioral or medical reasons. Rest assured though, that if your dog has a medical problem, the licking will be very different to the usual display of joy and a wagging tail. Dogs in pain or those with allergies will lick ‘themselves’ more so than you, and there will be other signs of discomfort, such as a hanging head or nibbling and biting at themselves. Dogs who suffer obsessive or compulsive behaviors may be prone to excessive licking. If this is your experience with your dog, your vet may need to check them out as soon as possible.
Health Problems
If your dog is excessively licking themselves, the floor, or even just licking the air in front of their face, this is a sign that something may be wrong. It could be physical or emotional, and your vet will need to check your dog as soon as possible. Pain and nausea often cause dogs to lick and gulp.
Anxiety in dogs will often manifest in excessive, compulsive behavior such as licking and chewing.

Try to recognize any patterns in the behavior, such as when it occurs, how long it lasts, does it stop if you take your dog for a walk or feed them? Observe your dog closely and note any relevant facts. Giving your vet this information will help them to make a correct diagnosis.
Dogs in The Wild
Puppies lick the mouths of their mother when she returns from hunting or feeding. This initiates regurgitation of the food so the puppies can eat. The mother also licks the puppies around the bottom and genitals to stimulate toileting, which she then consumes herself to keep the nest clean.

So, dogs are hard-wired to lick their loved ones as a sign of nurturing and affection.
Dogs Can Smell and Taste You
Dog’s noses are much more sensitive than humans. They can smell tiny traces of food on your face or lips, even if you ate hours ago. This is very attractive to your pup. Licking it off is how they groom you, while having a little tasty treat themselves. Even if there is no food smell, dogs seem to like the salty taste of human skin.
Dogs Lick to Get Attention
When our dog licks us, the first thing we do is give them something. A smile, a treat or a pet, either way it’s a positive reinforcement of that behavior. We also give our dogs attention if we need to calm them down, especially if they are licking incessantly or over-excitedly.

Sign of Submission
Dog’s feel safe and secure with their pack-leader. Licking can sometimes be a submissive gesture. Communication can be very subtle between dogs, and between dogs and humans.
Enjoyment and Exploration
Dogs can get bored or curious just like us, so sensing by licking can be an enjoyable way for them to just pass the time of day. It’s the most natural thing for them to do.

Should I Stop My Dog Licking Me?
Licking can be nothing more than pure affection and friendliness for you. If it’s constant though, it can be a little intrusive at times. Your pup can be trained not to lick you, but it will take time. You may require the help of a behaviorist if you’re unsure. Try to remember that dog’s can’t verbalize their feelings, so licking is a way for them to communicate something to you.
As long as your dog is happy, healthy, and enjoying life, they will always demonstrate their joy and love by licking you now and again. Enjoy it.