Maslow's hierarchy of needs theory explains that consumers progress through a set of motivation systems from basic physiological needs to achieving self-actualization. There are five key steps in the consumer decision making process: need recognition, information search, evaluation of alternatives, purchase decision, and post-purchase evaluation. Personal, social, and cultural factors influence consumers' decisions, along with reference groups. The decision making unit involves various roles like gatekeepers, influencers, users, deciders, and buyers that must be considered when marketing and selling products.