OED Definition: The science which treats of animals, constituting one of the two branches (zoology and botany) of Natural History or Biology, and comprising many subordinate branches, as ornithology, ichthyology, entomology, etc. (1)
Zoology is, as mentioned above, the study of animals. That includes everything from complex humans and dolphins, to the more simple sea sponge and amoeba. However this section is probably going to centre on human and mammalian science first before moving onto others.
In the course of looking at Zoology we will cover topics such as Physiology (the study of how the body works), Anatomy (the study of how the body is structured) and other more specific areas like embryology and development.