Psychology is the study of the mind and mental processes, especially in relation to behavior.
Clinical psychology is concerned with diagnosing and treating disorders of the brain, emotional disturbances, and behavior problems. Child psychology is the study of the mental and emotional development of children and is part of developmental psychology, the study of changes in behavior that occur through the life span. Cognitive psychology deals with how the human mind receives and interprets impressions and ideas. Social psychology looks at how the actions of others influence the behavior of an individual.
Psychologists are experts in psychology and are usually categorised under a number of mental health professions such as clinical and counseling psychologists. Psychologists can only use talk therapy as treatment; you must see a psychiatrist or other medical doctor to be treated with medication.