L'affresco è una pittura eseguita sull'intonaco fresco di una parete: il colore ne è chimicamente incorporato e conservato per un tempo illimitato.
Fresco (plural frescos or frescoes) is a technique of mural painting executed upon freshly laid, or wet lime plaster. Water is used as the vehicle for the dry-powder pigment to merge with the plaster, and with the setting of the plaster, the painting becomes an integral part of the wall. The word fresco (Italian: affresco) is derived from the Italian adjective fresco meaning "fresh".