Maslow's Hierarchy of Needs proposes that people are motivated to fulfill basic needs before moving on to other needs. The hierarchy consists of physiological needs, safety needs, social needs, esteem needs, and self-actualization needs. The theory maintains that lower level needs must be satisfied before progressing to meet higher level needs. Physiological needs are basic human needs like food, water, air and shelter. Safety needs include security and stability. Social needs involve love, belonging and acceptance. Esteem needs encompass self-respect and respect from others. Self-actualization refers to achieving one's full potential and fulfillment.