When a dog jumps on a human of its own free will, it is not "greeting" the human, it is asserting its dominance over the human; it is the dog communicating that it is alpha and/or wishes to own/control the human. A subordinate would never dream of running over and jumping on the alpha dog of the pack. Space is respect and lower members of the pack respect the higher members. If your dog jumps on humans, it does not respect them. Note: when a young puppy jumps on humans it is sometimes its attempt to reach one's face. Puppies need to be taught not to jump up on humans as this behavior will manifest into other meanings as the puppy grows up into an adult dog.

When your puppy reaches adolescence, he may be unable to control his impulses and start to test limits (just like a human child). Adolescent jumping up can turn into “nose boinking” which can lead to broken glasses or even a bloody nose. Jumping up often combines with mouthing behavior where the pup bites and grabs your hands, clothing or even your derriere in a grabbing game of tag.
Redirect with a sit command. The simple 'sit' command can be useful in many different situations. Most importantly, it is a great distraction technique for redirecting your dog's attention from an undesirable behavior, such as jumping up. When your dog jumps up on you, turn your back to them while keeping them in your peripheral vision. Ask her to sit and immediately praise her when she does so.

This week’s episode is on how to teach your dog to stop jumping up and instead greet people politely. Jack writes that he and his wife have taught their young dog that he gets attention only when all four paws are on the floor. But the dog jumps up on guests. His exuberant greetings are hard on children and old people. Today I’ll explain how to teach your dog that the best way to get people to say hi is just to sit there and not jump up.