Sigmund Freud was a foundational figure in the development of psychoanalysis, a revolutionary approach to psychology that emphasized the role of the unconscious mind. Freud introduced concepts such as repression, dream interpretation, and the Oedipus complex, which significantly influenced both psychotherapy and the understanding of human behavior. His theories proposed that unresolved conflicts from childhood could manifest as neuroses in adulthood, emphasizing the importance of childhood experiences. Freud's work laid the groundwork for modern psychological practices and shaped the discourse around mental health.