A mesa is a flat-topped hill or mountain with steep sides, commonly found in arid and semi-arid regions. The word "mesa" comes from the Spanish word for "table," reflecting its table-like appearance. Mesas are formed through erosion, where softer rock layers wear away, leaving behind the harder rock that creates the flat top. Mesas can vary in size and height, and they often serve as important habitats for various plants and animals. They are commonly associated with the landscapes of the American Southwest, particularly in areas like the Grand Canyon and Monument Valley.