Psychoanalysis is based on the theories of Sigmund Freud and his followers. There are at least 20 different theoretical orientations regarding the underlying theory of the understanding of human mentation and development, but essentially psychoanalysis deals with the investigation of the mind, a systematised body of knowledge about human behaviour, and a method of treatment of psychological or emotional illness.
Regular sessions of psychoanalysis provide a setting where unconscious patterns can be brought into awareness with a view to changing them. The client's relationship with the analyst is an important influence upon the client's unconscious ways of behaving and, in itself, becomes a central area of focus, highlighting the client's patterns within the relationship in the immediacy of the sessions.
Freudian psychoanalysis is a specific type of psychoanalysis in which the "analysand" verbalizes thoughts, through methods such as free association, fantasy, and dreams. The analyst interprets them for the client to create insight for the resolution of issues and problems in the clients life.
Freud believed that unacceptable thoughts from early childhood are repressed in the unconscious mind but continue to influence our feelings, thoughts, emotions and behaviour. These repressed feelings often surface in adulthood as conflicts, depression, etc or in dreams and/or creative activities. These unconscious aspects are explored in the therapy through the intervention of the analyst, confronting the client's pathological defenses, wishes and guilt.
Related UKCP modality sections:
Council for psychoanalysis and Jungian analysis (CPJA) | 
