"Cash cow" is a product, product group, or part of a business that generates a large portion of sales or profits on an ongoing basis and has a large market share in a stable, mature market.

The term comes from the BCG matrix, a portfolio analysis model developed in the early 1970s by the Boston Consulting Group (BCG). The model is widely used by business owners, managers, marketing people and consultants to determine which parts of a company generate the most value.

A cash cow is seen as a stable and reliable source of income for a company, which the company can use to fund other investments and growth opportunities.