The kingdom Animalia consists of, you guessed it, animals. Animals are defined as being multicellular and depend on organisms that can manufacture their own food, usually by the process of photosynthesis. Believe it or not, mammals and their fellow vertebrates only make up a small part of this kingdom. However, most people recognize vertebrates as animals more often.
Most animals have a nervous system, sense organs, and ways to move.
They also usually are capable of catching their food, eating, and digesting it. One interesting fact is that Animalia is now seen to be the smallest of the kingdoms.