An arrangement whereby the seller of some product or service requires, as a condition to the sale of that product (the tying product), that the buyer purchase some additional product (the tied product). The tying arrangement is unlawful when the seller has some power over the market for the tying product. Tying arrangements are generally per se illegal, assuming that the selling firm as the market power to force the arrangement upon its customers.
Tying is the practice of making the sale of one good (the tying good) to the de facto or de jure customer conditional on the purchase of a second distinctive good (the tied good). A classic example of de facto tying is the selling of razors at a loss and making the profit on the blades. Cell phones and printers sold at below cost, the profit to be made on the subsequent minutes or printer cartridges, are also common.
A marketing technique whereby a firm producing a product that will function only if used in conjunction with another product requires its customers to buy the latter product from it, rather than from alternative suppliers.