Why do dogs lick themselves
and other dogs?

This is the best way dogs have to sanitize and sterilize themselves making it easier for injuries to heal. Speculating we could say it is also related to being bored or nervous.

Nature is so wise that in order to preserve the species it has given female dogs the wisdom to lick their puppies so as to eliminate smells that predators could easily spot. Moreover,, male dogs lick female parts to see if they are ready to be bred. And female dogs do the same to male dogs to see whom they've been with. Just checking out its hang outs!

But dogs lick among themselves as if it were friends patting each other, or just because they can probably find a smoothie.