Mediation, in a broad sense, comprises an act of bringing two states, sides or parties closer or together. This article discusses the communication sense of the term. Separate articles, cultural and biological, treat of other senses of mediation.

Mediation consists of a process of alternative dispute resolution in which a (generally) neutral third party, the mediator, using appropriate techniques, assists two or more parties to help them negotiate an agreement, with concrete effects, on a matter of common interest. More generally speaking, the term mediation covers any activity in which an impartial third party (often a professional) facilitates an agreement on any matter 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 include commerce, legal disputes and diplomacy, but forms of mediation appear in other fields as well. Mediation in marriage technically belongs in the category, although it has followed its own peculiar history since the times of ancient Greeks: compare marriage counselling.

The term comes from a Greek word meaning "fleshy growth." Bone tumors (osteosarcomas) are also called sarcomas, but are in a separate category because they have different clinical and microscopic characteristics and are treated differently. Osteogenic sarcoma or osteosarcoma is one of the most common childhood bone cancers. Soft tissue sarcomas are more common in adults than in children. In all, sarcomas constitute less than 1% of all cancers. Its treatment is made more difficult with the existence of more than 70 varieties. Gastrointestinal stromal tumor (GIST) is the most common form of sarcoma, with approximately 3000-3500 cases per year in the United States.