A pyramid scheme is a business model which, rather than earning money (or providing returns on investments) by sale of legitimate products to an end consumer, mainly earns money by recruiting new members with the promise of payments (or services). As the number of members multiplies, recruiting quickly becomes increasingly difficult until it is impossible, and therefore most of the newer recruits do not make a profit. As such, pyramid schemes are unsustainable. The unsustainable nature of pyramid schemes has led to most countries outlawing them as a form of fraud.
Pyramid schemes have existed since at least the mid-to-late 19th century in different guises. Some multi-level marketing plans have been classified as pyramid schemes.