Self-realization is an expression used in Western psychology, philosophy, and spirituality; and in Indian religions. In the Western, psychological understanding it may be defined as the "fulfillment by oneself of the possibilities of one's character or personality." In the (South) Asian understanding, Self-realization is liberating knowledge of the true Self, either as the permanent undying Atman, or as the absence (sunyata) of such a permanent Self.
Merriam Webster's dictionary defines self-realization as:
Fulfillment by oneself of the possibilities of one's character or personality.
In the Western world "self-realization" has gained great popularity. Influential in this popularity were psycho-analysis, humanistic psychology, the growing acquaintance with Eastern religions, and the growing popularity of Western esotericism.
Though Sigmund Freud was sceptical of religion and esotericism, his theories have had a lasting influence on Western thought and self-understanding. His notion of repressed memories, though based on false assumptions, has become part of mainstream thought.
Freud's ideas were further developed by his students and neo-psycho-analysts. Carl Jung, Erik Erikson, and Winnicott have been especially important in the Western understanding of the self. But other alternatives have also been developed.
Jung developed the notion of individuation, the lifelong process in which the centre of psychological life shifts from the ego to the self.
Erikson described human development throughout the life-span in his theory of psychosocial development.
Winnicott developed the notion of the true self.
Roberto Assagioli developed his approach of Psychosynthesis, an original approach to psychology.