Products pass through distinct life cycle stages characterized by changing sales, costs, and profits. The four stages are: introduction (low sales, high costs), growth (rising sales and profits), maturity (peak sales, high competition), and decline (falling sales and profits). Strategies must adapt to the challenges of each stage, focusing on creating awareness early, maximizing market share in growth, defending share in maturity, and reducing expenditures in decline. Modifying the product, market, or marketing mix can sometimes prolong the maturity stage.