Contract between a buyer and a seller, whereby the former agrees to purchase from the latter a fixed quantity of a product for a given price over a certain period of time. Irrespective of the quantity which is finally needed and transferred, the buyer is bound by its commitments and is required to pay for the whole volume of sales at the contractual terms agreed upon.

Source: Glossary of terms used in EU competition policy, Antitrust and control of concentrations, European Commission, 2002