This document discusses demand and game theory. It defines demand, the law of demand, and the assumptions behind the law of demand. It explains why demand curves slope downward, including substitution effect, income effect, and diminishing marginal utility. It defines individual demand, market demand, demand functions, and elasticity of demand. It discusses objectives and methods of demand forecasting. Finally, it provides a brief definition of game theory as applying mathematics to strategic situations where an individual's success depends on others' choices.