Psychology (from Greek: ψυχή, psukhē, "spirit, soul"; and λόγος, logos, "knowledge") is both an academic and applied discipline involving the scientific study of mental processes and behavior. Psychologists study such phenomena as perception, cognition, emotion, personality, behavior, and interpersonal relationships. Psychology also refers to the application of such knowledge to various spheres of human activity, including issues related to daily life—e.g. family, education, and work—and the treatment of mental health problems.

As a social science, psychology attempts to understand the role human behavior plays in social dynamics (e.g., culture, economics, and politics). Although psychology differs from biology and neuroscience as a field of study, current psychological science incorporates physiological and neurological processes into its conceptions of mental functioning. Psychology includes many sub-fields of study and application concerned with such areas as human development, sports, health, industry, forensics, and spirituality.