Fresco meaning "fresh" in Italian is the art of painting on fresh plaster with pigments diluted in water. The painting must be done quickly before the base has time to dry, as once it has dried, the painting becomes an actual part of the wall. This is what gives the fresco its uniquely soft colors and delicate transparency.

This technique of painting was known from antiquity. Frescoes were extensively used as wall decoration in Roman times. Indeed, archeologists have unveiled a series of frescoes with explicit sex scenes in the ancient Roman city of Pompeii. Frescoes were especially popular in the Renaissance and Baroque periods and was used to decorate the walls and ceilings of churches, public buildings, and private villas..

Michelangelo painted "The Last Judgment" 1535-1541 on the altar wall of the Sistine Chapel. The painting includes a stunning 390 figures surrounding Christ.