Psychology, the science of the behavior and mental processes of humans and other higher animals. It is concerned with the responses of individuals and groups to their physical and social environments. Psychologists study the experiences and reactions of people, including their sensations and perceptions, feelings and emotions, thoughts, and motives.

As a basic science, psychology is concerned with learning the facts of human nature and formulating general principles in regard to them. As an applied science it is concerned with solving human problems. Psychological findings and theories have had a profound influence on child rearing, education, medicine (especially the diagnosis and treatment of mental illness), law, criminology, literature, art, industry, and politics.

In one sense, psychology is as old as the human race, because people have always been interested in themselves and their fellows. They have tried to analyze their own thoughts and feelings, have observed the behavior of those around them, and have offered numerous theories of the human mind and of human activity. However, psychology as a field of scientific inquiry did not have its beginnings until late in the 19th century. It is a biological science closely related to physiology. It is also one of the social and behavioral sciences.

Psychologists are engaged in research, teaching in colleges and universities, counseling, or psychiatric work. Many are employed in primary and secondary schools, in hospitals, and in industry.