In international relations, a concession is a "synallagmatic act by which a State transfers the exercise of rights or functions proper to itself to a foreign private test which, in turn, participates in the performance of public functions and thus gains a privileged position vis-a-vis other private law subjects within the jurisdiction of the State concerned." International concessions are not defined in international law and do not generally fall under it. Rather, they are governed by the municipal law of the conceding state. There may, however, be a law of succession for such concessions, whereby the concession is continued even when the conceding state ceases to exist.

In international law, a lease is "an arrangement whereby territory is leased or pledged by the owner-State to another State. In such cases, sovereignty is, for the term of the lease, transferred to the lessee State." The term "international lease" is sometimes also used to describe any leasing of property by one state to another or to a foreign national, but the normal leasing of property, as in diplomatic premises, is governed by municipal, not international, law. Sometimes the term "quasi-international lease" is used for leases between states when less than full sovereignty over a territory is involved. A true international lease, or "political" lease, involves the transfer of sovereignty for a specified period of time. Although they may have the same character as cessions, the terminability of such leases is now fully accepted.