In archaeological terms, graffiti is a mark, image or writing scratched or engraved into a surface. There have been numerous examples found on sites of the Roman Empire, including taverns and houses, as well as on pottery of the time. In many cases the graffiti tend toward the rude, with a line etched into the basilica in Pompeii reading "Lucilla made money from her body," phallic images, as well as erotic pictures. Other graffiti took on a more innocent nature, taking the form of simple pictures or games. Although many forms of Roman graffiti are indecipherable, studying the graffiti left behind from the Roman Period can give a better understanding of the daily life and attitudes of the Roman people with conclusions drawn about how everyday Romans talked, where they spent their time, and their interactions within those spaces.

A graffito, in an archaeological context, is a deliberate mark made by scratching or engraving on a large surface such as a wall. The marks may form an image or writing. The term is not usually used for the engraved decoration on small objects such as bones, which make up a large part of the art of the Upper Paleolithic, but might be used for the engraved images, usually of animals, that are commonly found in caves, though much less well known than the cave paintings of the same period; often the two are found in the same caves. In archaeology, the term may or may not include the more common modern sense of an "unauthorized" addition to a building or monument. Sgraffito, a decorative technique of partially scratching off a top layer of plaster or some other material to reveal a differently colored material beneath, is also sometimes known as "graffito".