Petroglyphs, man-made carvings on rock or stone, may be the most common form of rock art but it isn't the only. Pictographs, man-made drawings and paintings on rock and caves, were made prehistoric peoples around the world. Petroforms, the placement of rocks and boulders to form patterns and shapes, were made by many different peoples too. Inukshuk, rock piles or single standing rocks made by the Inuit, are found only in the Arctic. Geoglyphs, also called intaglios, are giant etchings in the ground. While modern day artists carve letters and words in hills just about everywhere, geoglyphs were once made by prehistoric peoples in harsh deserts only.