Sigmund Freud was an Austrian neurologist and the founder of psychoanalysis, a method for treating mental illness and understanding human behavior. He introduced concepts like the unconscious mind, which suggests that our thoughts and feelings are often influenced by hidden desires and memories. Freud's theories emphasized the importance of childhood experiences in shaping personality and behavior. Freud is also known for his ideas about dream interpretation and the Oedipus complex, which explores the dynamics of family relationships. His work has had a profound impact on psychology, literature, and art, making him one of the most influential figures in modern thought.