Multi-level marketing (MLM), also called network marketing or pyramid selling, is a controversial and sometimes illegal marketing strategy for the sale of products or services in which the revenue of the MLM company is derived from a non-salaried workforce selling the company's products or services, while the earnings of the participants are derived from a pyramid-shaped or binary compensation commission system.

In multi-level marketing, the compensation plan usually pays out to participants from two potential revenue streams: the first is based on a sales commission from directly selling the product or service, while the second is paid out from commissions based upon the wholesale purchases made by other sellers whom the participant has recruited to also sell product. In the organizational hierarchy of MLM companies, recruited participants (as well as those whom the recruit recruits) are referred to as one's downline distributors. MLM salespeople are, therefore, expected to sell products directly to end-user retail consumers by means of relationship referrals and word of mouth marketing, but more importantly they are incentivized to recruit others to join the company's distribution chain as fellow salespeople so that these can become downline distributors.

According to a study of 350 MLM companies in the United States, at least 99% of recruits lose money. Nonetheless, MLM companies function because downline participants are encouraged to hold onto the belief that they can achieve large returns, while the statistical improbability of this is de-emphasized. MLM companies have been made illegal or otherwise strictly regulated in some jurisdictions as merely variations of the traditional pyramid scheme.

Independent non-salaried participants, referred to as distributors (variously called "associates", "independent business owners", "independent agents", "affiliates", etc.), are authorized to distribute the company's products or services. They are awarded their own immediate retail profit from customers plus commission from the company, not downlines, through a multi-level marketing compensation plan, which is based upon the volume of products sold through their own sales efforts as well as that of their downline organization.

Independent distributors develop their organizations by either building an active consumer network, who buy direct from the company, or by recruiting a downline of independent distributors who also build a consumer network base, thereby expanding the overall organization.^{[citation needed]}

The combined number of recruits from these cycles is the sales force, called the salesperson's "downline". This "downline" is the pyramid in MLM's multiple-level structure of compensation.

The overwhelming majority of MLM participants—99.6% of participants, according to one study—lose money. Indeed, the largest proportion of participants must operate at a net loss (after expenses are deducted) so that the few individuals in the uppermost level of the MLM pyramid can derive their significant earnings. Said earnings are then emphasized by the MLM company to all other participants to encourage their continued participation at a continuing financial loss.

Many MLM companies generate billions of dollars in annual revenue and hundreds of millions of dollars in annual profit. However, profits accrue to the detriment of most of the company's constituent workforce (the MLM participants). Only some of the profits are then shared with individual participants at the top of the MLM distributorship pyramid. The earnings of those top few participants are emphasized and championed at company seminars and conferences, thus creating the illusion that participants in the MLM can become financially successful. This is then advertised by the MLM company to recruit more distributors in the MLM with an unrealistic anticipation of earning margins which are in reality merely theoretical and statistically improbable.