Motivation is defined as the drive to satisfy a need. Some motives are socially learned (e.g. wanting to get married) and others are instinctive (e.g. eating when hungry). Many motives are unconscious but active in that they influence everyday buying behaviour.
Many theories of motivation have been developed to explain why consumers behave in certain ways. Notables are theories of Marshall, Freud, Veblen, Herzberg and Maslow.