A petroglyph is an image created by removing part of a rock surface by incising, picking, carving, or abrading, as a form of rock art. Outside North America, scholars often use terms such as "carving", "engraving", or other descriptions of the technique to refer to such images. Petroglyphs, estimated to be 20,000 years old are classified as protected monuments and have been added to the tentative list of UNESCO's World Heritage Sites. Petroglyphs are found worldwide, and are often associated with prehistoric peoples. The word comes from the Greek prefix petro-, from πέτρα petra meaning "stone", and γλύφω glýphō meaning "carve", and was originally coined in French as pétroglyphe.
In scholarly texts, a petroglyph is a rock engraving, whereas a petrograph (or pictograph) is a rock painting. In common usage, the words are sometimes used interchangeably. Both types of image belong to the wider and more general category of rock art or parietal art. Petroforms, or patterns and shapes made by many large rocks and boulders over the ground, are also quite different. Inuksuit are not petroglyphs, but human-made rock forms found in Arctic regions.
Petroglyphs have been found in all parts of the globe except Antarctica, with highest concentrations in parts of Africa, Scandinavia and Siberia, many examples of petroglyphs found globally are dated to approximately the Neolithic and late Upper Paleolithic boundary (roughly 10,000 to 12,000 years ago).
Around 7,000 to 9,000 years ago, following the introduction of a number of precursors of writing systems, the existence and creation of petroglyphs began to suffer and tail off, with different forms of art, such as pictographs and ideograms, taking their place. However, petroglyphs continued to be created and remained somewhat common, with various cultures continuing to use them for differing lengths of time, including cultures who continued to create them until contact with Western culture was made in the 19th and 20th centuries.