One of the four categories on the Boston Matrix – a tool of product portfolio analysis that classifies a business’s products according to market share and rate of market growth. Stars are products with a large share of a high growth market. They generate lots of revenue for the business but, as the market is growing rapidly, they often require considerable investment in promotion and, possibly, in additional capacity in order to maintain their dominant position. As a result, the cash flow from stars can be low and even negative in some cases.