Psychology is the scientific study of the mind and behavior. It originated in the late 19th century and has since developed into various subfields that seek to understand cognition, emotion, sensation, perception and human development. There are three types of pure psychology: experimental, physiological and comparative psychology. Psychologists can also be categorized into clinical, counseling, school and industrial/organizational psychologists. Common methods used in psychology include observation, surveys, case studies and experiments. Understanding human behavior and mental processes is important for healthcare professionals to effectively treat patients, communicate diagnoses and provide support.