The life cycle of a product comprises different phases usually described as introduction, growth, maturity and decline, with each phase presenting different challenges and opportunities. In practice, it can be difficult to define accurately which stage of the life cycle a category is in as individual product life cycles can be very short. Mobile telephone handsets may collectively be in their growth phase, but individual models may have a life cycle of between 90 and 360 days. When analysing supply markets it can be helpful to understand where the category is in its life cycle, as the marketing strategy may change as the category matures. For example, the supplier’s pricing strategy in the introductory phase may involve premium pricing, while the pricing strategy during the growth period may involve significant discounting.