Maslow's hierarchy of needs proposes that human motivations are arranged in a pyramid with the most basic needs at the bottom and psychological needs at the top. The lowest level includes physiological needs like food, water, shelter and sex. The next level is safety needs including security and health. Belongingness and love needs, such as friendship and intimacy, come next. Esteem needs involve respect and self-respect. The top level is self-actualization where one reaches their full potential. Maslow believed lower level needs must be met before progressing to meet higher level needs.