[[File:Pyramid scheme diagram.svg|thumb|upright=1.3|The unsustainable exponential progression of a classic pyramid scheme in which every member is required to recruit six new people. To sustain the scheme, the 2.2 billion people in the 12th layer would be required to recruit 13.1 billion more people for the 13th layer, even though there are not nearly enough [[World population|people in the world]] to achieve that.]]
A '''pyramid scheme''' is a [[business model]] which, rather than earning money (or providing returns- on- investments) by sale of legitimate [[product (business)|products]] to an end consumer, it mainly earns money by recruiting new members with the promise of payments (or services).<ref>{{Britannica URL|topic/pyramid-scheme|pyramid scheme}}</ref><ref>{{cite web |url=https://consumer.sd.gov/fastfacts/marketing.aspx |url-access= |title=Multi-Level Marketing vs Pyramid Schemes |author=Website admin. |year=2024 |department=Consumer Protection |website=consumer.sd.gov |publisher=Office of the Attorney General of South Dakota |___location=|type= |access-date=February 18, 2024 |url-status= |archive-url= |archive-date= |quote=The difference between a pyramid scheme and a lawful MLM program is that there is no real product that is sold in a pyramid scheme. Participants attempt to make money solely by recruiting new participants into the program. The hallmark of these schemes is the promise of sky-high returns in a short period of time for doing nothing other than handing over your money and getting others to do the same. }}</ref> As the number of members multiplies, recruiting quickly becomes increasingly difficult until it is impossible, whileand therefore most of the newer recruits do not make a profit due to recruiting being more difficult. As such, pyramid schemes are unsustainable. The unsustainable nature of pyramid schemes has led to most countries outlawing them as a form of [[Fraud|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.<ref name="Smith1984" />
