The document discusses the product life cycle (PLC), which describes the stages through which a product passes from introduction to decline. It defines the PLC and outlines its key stages - introduction, growth, maturity, and decline. Each stage is characterized by different sales volumes, prices, profits, and marketing strategies. Factors like technology changes, competition, and demand can affect the PLC. Marketers must adapt their strategies at each stage to maximize sales and profits over the lifetime of the product.