Psychology deals mainly with humans but also sometimes with nonhuman animals. Because psychology may be difficult to study as a whole, psychologists often only look at small parts of it at one time. Psychology has much in common with many other fields, and overlaps with many of them. Some of these fields are medicine, ethology, computer science, and linguistics.
Psychology has been split up into smaller parts called branches. These are subjects in psychology that try to answer a particular group of questions about how people think. Some branches of psychology that are often studied are: