The subconscious is a parts of the mind of which a person is not fully aware or in control. Subconscious thoughts are thoughts which are below the level of consciousness, which is the part that we perceive to be "ourselves" in our waking lives.
The subconscious level of the mind is important to many aspects of psionics and magick, particularly as these activities often rely on the precise mental state of the practicioner. In some instances, metaphysical acts (particularly, psionic ones) have been known to occur by entirely subconscious means, without any direct awareness. These incidents are generally known as geisting.
Though the subconscious is often inadequately compared to (but may be in a better state of contact with) the concept of one's higher self (also called the oversoul, superconscious, or superego).