This chapter discusses motivation and different motivational theories. It defines motivation as a need or desire that energizes and directs behavior. Some key motivational concepts discussed include drive-reduction theory, which proposes that physiological needs create arousal states that motivate behavior; Maslow's hierarchy of needs, which arranges human needs in a pyramid from basic physiological needs to higher psychological needs; and achievement motivation theory, which suggests people are motivated to accomplish things and master skills. The chapter also covers motivation related to hunger, sex, and work performance.