Mediation is a process of alternative dispute resolution in which a neutral third party, the mediator, assists two or more parties to help them negotiate an agreement, with concrete effects, on a matter of common interest; lato sensu is any activity in which an agreement on any matter is researched by an impartial third party, usually a professional, in the common interest of the parties involved.

Mediation applies to different fields, with some common peculiar elements and some differences, for each of its specialties. The main fields of mediation are commerce, legal dispute and diplomacy, but forms of mediation can be found in other fields as well. Mediation in marriage is technically admitted in the category, although it follows its own peculiar history since the times of ancient Greeks.

The activity in itself is indeed very ancient, presumably started with Phoenician commerce (but its use is supposed in Babylon, too), and developed in Greece (where the mediator is called proxenetas - not in the sense of marriage mediator), then in Roman civilization, where mediation is recognised in Roman law starting from Justinian's Digest. In Rome the mediator was called with a variety of names, including internuncius, medium, intercessor, philantropus, interpolator, conciliator, interlocutor, interpres, and finally mediator. During the Middle Ages, mediation was considered differently, sometimes forbidden, or its practice restricted to centralized authorities. In some cultures, it was instead a sacred figure, tributed a particular respect, partly coincident with that of traditional wise men.