A defense mechanism is a psychological strategy that an individual uses to protect themselves from anxiety or stress, often by avoiding or minimizing emotional pain. These mechanisms can take many forms and may be conscious or unconscious, but they generally serve as coping strategies for dealing with difficult situations or feelings. Some common defense mechanisms include denial (refusing to accept reality), repression (blocking out memories or experiences), rationalization (making excuses or justifications), projection (attributing one's own feelings or motives to others), and regression (returning to earlier, less mature behavior patterns).