Ventifacts are rocks that have been abraded, pitted, etched, grooved, or polished by wind-driven sand or ice crystals.

They are geomorphic features as they are morphed or changed by nature. They are typically found in arid environments where there is little vegetation to interfere with the wind path. They occur where there are frequently strong winds, and where there is a steady but not overwhelming supply of sand.

When ancient ventifacts are preserved without being moved or disturbed, they may serve as a paleo-wind indicators. The wind direction at the time the ventifact formed will be parallel to grooves or striations cut in the rock.

An example of a Martian ventifact was named Jake Matijevic. By analyzing its shape, it was possible to reconstruct the main wind direction which sculpted the rock