Frescos are a type of mural painting done on wet plaster. This technique was used in the Renaissance period and is still used today. Frescos are created by applying pigments to wet plaster, which then dries and becomes part of the wall. The term 'frescos' is derived from the Italian word for fresh, as the plaster must be wet when the painting is applied. Paintings on wet plaster, or frescos, are a popular form of art that can be found in many churches, palaces, and other public buildings.