The product life cycle consists of five primary stages: development, introduction, growth, maturity, and decline. During development, sales are zero and costs are high. In the introduction phase, sales and profits are low. The growth stage sees rapidly rising sales and profits. Maturity is marked by slowing sales growth as the market becomes saturated. Finally, the decline phase has falling sales and profits, and some companies withdraw their products from the market. Each stage poses different challenges and opportunities for marketers and requires different strategies.