The document discusses product life cycles, which have four distinct stages: introduction, growth, maturity, and decline. During each stage, a product experiences different sales trends and requires different business strategies. For example, McDonald's is currently in the maturity stage for its products, where strong sales growth is diminishing and competition from similar products like Burger King is increasing. At this late stage, the primary objectives are defending market share and maximizing profits through product enhancements or new offerings.