Dorothea Orem's Self-Care Deficit Theory of Nursing focuses on the concepts of self-care, self-care deficit, and nursing systems. The theory proposes that individuals require self-care to maintain health but may experience self-care deficits requiring nursing care. Orem identified three types of nursing systems - wholly compensatory, partially compensatory, and supportive-educative - to describe the level of care and support needed when a self-care deficit exists.