From the information-processing perspective of the Level Map, we can see that the vast majority of what goes on in the mind are things that we are not conscious of. The lower levels in the level map are things that are automated, that happen without any conscious intervention or introspection. For example, part of the puzzle of an Optical illusion is that visual perception is automated, so our knowledge of the inaccuracy of the perception has no effect.
This emphasis on the overwhelming predominance of unconscious processing leads to a view of the unconscious mind as necessarily highly effective and in some sense “smart”, as in the Adaptive unconscious. There are a variety of theories that acknowledge that the mind has effective unconscious means of accomplishing various tasks which are in addition to, and complement conscious mental processing. See Dual process theory. Broadly, the idea is that some tasks (such as visual perception) are both important and ill-suited to conscious management, so are implemented unconsciously. A skill (such as driving) may also require a great deal of conscious attention at first, but with practice becomes largely automated.
Note that mental capabilities which existed in non-conscious human predecessors will tend to also be unconscious in humans because of Evolutionary Conservation.
This meaning of differs somewhat from the usage in Depth psychology (see Psychoanalytic unconscious and Shadow (psychology)) See also Unconscious mind. These older concepts of the unconscious are not actually invalidated by the newer information processing theories of the Adaptive unconscious. The unconscious of depth psychology arises from introspective examination, and necessarily deals with that subset of mental phenomena that can come into our awareness, and particularly relates to the sometimes-fluid nature of the interface between consciousness and intuitive processes.