A cave is a natural underground space that is large enough for a human to enter. Caves are formed through various geological processes, such as erosion by water, volcanic activity, or the dissolution of limestone. They can be found in many environments around the world, from mountains to coastal areas. Caves often contain unique ecosystems and can be home to various species, including bats and cave-dwelling insects. Some famous caves, like Carlsbad Caverns in the United States and Lascaux in France, are known for their stunning rock formations and ancient cave paintings, respectively.