Sigmund Freud (1894, 1896) noted a number of ego defenses which he refers to throughout his written works. His daughter Anna (1936) developed these ideas and elaborated on them, adding ten of her own. Many psychoanalysts have also added further types of ego defenses.
Defense mechanisms are psychological strategies that are unconsciously used to protect a person from anxiety arising from unacceptable thoughts or feelings.
We use defense mechanisms to protect ourselves from feelings of anxiety or guilt, which arise because we feel threatened, or because our id or superego becomes too demanding. They are not under our conscious control, and are non-voluntaristic.
Ego-defense mechanisms are natural and normal. When they get out of proportion (i.e., used with frequency), neuroses develop, such as anxiety states, phobias, obsessions, or hysteria.
Courtesy : simplypsychology