A most favoured nation clause (also called a most favoured customer clause or most favoured licensee clause) is a contract provision in which a seller (or licensor) agrees to give the buyer (or licensee) the best terms it makes available to any other buyer (or licensee). In some contexts, the use of such clauses may become commonplace, such as when online ebook retailers contract with publishers for the supply of e-books. Use of such clauses, in some contexts, may provoke concerns about anticompetitive influences and antitrust violations, while in other contexts, the influence may be viewed as procompetitive.