An endorheic basin is a closed drainage basin that does not allow water to flow out to the ocean or sea. Instead, water that enters these basins either evaporates or seeps into the ground. This results in the accumulation of water in lakes or salt flats, often leading to high salinity levels due to evaporation. These basins can be found in various regions around the world, such as the Great Basin in the United States and the Caspian Sea area. Endorheic basins are significant for understanding local ecosystems and hydrology, as they influence the distribution of flora and fauna in their environments.