Psychology is the science of human behavior. This means that psychology is focused on what people do and why they do it. Psychology is a research-based bridge between the fields of sociology on one side and biology on the other. As a science, psychology uses research where experiments are designed to test why people do what they do. Psychology has very broad applications. Employees with psychology degrees work in clinical and mental health settings, industry and business (including sales and marketing), education, medicine, and many other fields.