Motivation is a complex process that influences human behavior. There are several theories that seek to explain what motivates individuals and impacts their productivity. Maslow's hierarchy of needs proposes that people are motivated to fulfill basic physiological needs before pursuing safety, love, esteem and self-actualization. Herzberg's two-factor theory distinguishes between hygiene factors like salary that prevent dissatisfaction and motivators like achievement that create satisfaction. McClelland's theory focuses on three needs - achievement, power and affiliation - that influence behavior. Equity theory, expectancy theory and goal-setting theory are examples of process theories that examine how people's motivation is affected by expectations, outcomes and goal-setting.