Sigmund Freud was the originator of psychoanalysis, and contributed many psychodynamic theories to popular understanding, including the notion that human emotions and actions are largely controlled by unconscious motivations and that the psyche has three notable parts: Id, Ego and Superego. Freud also introduced the psychosexual stages of development.
According to Freud, the human mind has three levels: consciousness, which refers to the things people focus on at any given moment; the preconscious, consisting of everything memory can retrieve; and the unconscious, the real root of most human behavior.
Freud's theory of psychosexual development and the Oedipus complex was his most controversial. Believing that children have a libido, he theorized that all children move through distinct stages of development and naturally seek pleasure from various parts of their body, from the oral stage through the anal, phallic, latent and genital stages.