A mesa is a flat-topped hill or mountain with steep sides, commonly found in arid and semi-arid regions. The term "mesa" comes from the Spanish word for "table," reflecting its table-like appearance. Mesas are formed through erosion, where softer rock layers are worn away, leaving behind a harder rock layer that creates the flat top. Mesas can vary in size and are often surrounded by canyons or valleys. They are significant in geography and ecology, providing unique habitats for various plants and animals. Famous examples of mesas include the Monument Valley in the United States and the Table Mountain in South Africa.