The difference between the conscious and unconscious mind is generally clear. You are conscious when you are awake, and unconscious when you are asleep (and during certain medical conditions we will not discuss here). Planning, decision making, working, studying, and other everyday activities are under control of the conscious mind. Those pesky nighttime dreams bubble up from the unconscious.
Although consciousness has been around for all of history, and before, it wasn't really reognized and studied until the end of the 18th century, when it was addressed by philosophers such as John Locke. They were looking at the idea of consciousness of self. Some think that being aware of one's self is what sets humans apart from other animals.
"Unconscious" has other connotations, so we generally use the term "subconscious" for the same concept in hypnosis. Freud's subdivision of mind into ego (mostly conscious), id (unconscious), and superego (some of each), is not useful for our purposes, except to note that the superego functions as conscience or moral judge, and as such is contained in our concept of the subconscious.
Because much of what's in your subconscious helps you to get along in society, the conscious mind defends it. This reveals a problem with positive thinking. It stays in the conscious and doesn't usually get through to the subconscious, where change is made. Getting through to the subconscious is the task of self-hypnosis.
