A lake is a large body of water surrounded by land, typically filled with freshwater or saltwater. Lakes can vary greatly in size and depth, and they play a crucial role in the ecosystem by providing habitats for various species of plants and animals. They are also important for human activities such as recreation, fishing, and water supply. Lakes are formed through various geological processes, including glacial activity, tectonic movements, and volcanic eruptions. Some well-known examples include the Great Lakes in North America and Lake Baikal in Siberia, which is the deepest lake in the world. These natural wonders are not only beautiful but also vital for biodiversity and climate regulation.