The product lifecycle has four stages: Introduction, Growth, Maturity, and Decline. Each stage has different characteristics for sales, profits, and marketing strategy.
During Introduction, sales are low and marketing costs are high. In Growth, sales increase rapidly. At Maturity, the market becomes saturated and competition intensifies. In Decline, sales gradually decrease.
For example, cassette players are in decline, while smartphones are at maturity. Successful companies adapt their strategies at each stage, investing in innovation to create new products before existing ones decline.