Synopsis Psychology is the science of individual or group behaviour. Psychology is intimately related to the biological and social sciences. Some of the divisions within psychology are applied fields, while others are more experimental in nature. The various applied fields include clinical, counselling, industrial, engineering, or personnel, consumer, and environmental. The most important of these specialities, clinical psychology, is concerned with the diagnosis and treatment of mental disorders. Industrial psychology is used in employee selection and related contexts in business and industry. The broad field known as experimental psychology includes specializations in child, educational, social, developmental, physiology, and comparative psychology. Of these, child psychology applies psychological theory and research methods to children; educational psychology is concerned with learning processes and problems associated with the teaching of students; social psychology is concerned with group dynamics and other aspects of human behaviour in its social and cultural setting; and comparative psychology deals with behaviour as it differs from one species of animal to another. The issues studied by psychologists cover a wide spectrum, comprising learning, cognition, intelligence, motivation, emotion, perception, personality, mental disorders, and the study of the extent to which individual differences are inherited or are shaped environmentally, known as behaviour genetics. This work gives encyclopaedic information on psychology with implied inclination towards teaching aspect of the subject.