This document classifies and describes various defense mechanisms used by the ego to manage internal conflicts and modulate drive expression. It categorizes defenses as narcissistic-psychotic, immature, neurotic, or mature. Narcissistic-psychotic defenses like projection, denial, and distortion grossly reshape reality. Immature defenses seen in adolescents include acting out, blocking, hypochondriasis, and passive-aggressive behavior. Neurotic defenses like rationalization, displacement, dissociation, and repression help control anxiety in a socially acceptable way. Mature defenses such as anticipation, humor, sublimation, and suppression promote healthy adaptation and integration of needs.