Sigmund Freud, a psychoanalytic psychologist, explained defense mechanisms as unconscious forces that react to conflicts by acting in defense of the ego. Defense mechanisms protect the conscious mind from overwhelming feelings or anxiety-producing thoughts. There are at least 10 different defense mechanisms.
Freud wrote about many different types of ego defenses throughout his writings. After he died, his daughter, Anna Freud, compiled these various defense mechanisms, defined them in detail and added some of her own concepts in her book, "The Ego and the Mechanisms of Defense."
In Freud's personality topography, defense mechanisms protect the ego, which is the conscious part of the person that interacts with reality, from conflicts between reality and its constraints, the id, which is the impulsive aspect of one's personality that seeks fulfillment of wants, and the superego, which is the moral part of personality. These conflicts create anxiety, which Freud characterized as an unpleasant inner state that people attempt to avoid. The three types of anxiety are neurotic, reality and moral.
Ego defense mechanisms are natural and normal. The unconscious mind automatically employs a number of defense mechanisms on a daily basis, and these mechanisms can be adaptive. When these mechanisms grow out of proportion or are overused, neuroses such as phobias develop.