For most dogs barking is about protection and warning. They bark to warn people and animals that this territory is claimed. They bark to say this is my food or my toy or my human, so stay away. But yapping is all about excitement. Dogs will yap when their owner or friend is approaching. They will yap when you are heading to that cabinet or shelf where they know their treats are located. They will yap when you are opening up the package that contains a new toy.