What is psychology and why do we study it?

1. I think psychology is the study of how our brains work.
2. The Science that deals with mental processes and behavior. (www.answers.com/topic/psychology)

3. We need to study psychology because it is important for us to know how our brain controls our body. We also learn parts of how the brain works, our memory, how do we learn, our personality, development etc. It is essential because its not only how we think but how other animals think so its very useful to know this in many ocassions.