Dogs lick people's faces for a few different reasons, but in many cases it's a sign of love and affection. Puppies typically lick faces even more than adult dogs. This behavior comes from wolf cubs, who lick their mothers' faces to signal hunger so they can be fed. Dogs don't feed their young the same way wolves do, but the licking instinct remains. A dog may also lick you in a submissive way, to let you know that it is not a threat. And of course, your licking dog may also simply be grooming you. Dogs groom each other as a gesture of intimacy when a solid bond is in place, so you can definitely take grooming as a sign of love from your dog.