Most lakes are freshwater, and most lakes are found in the Northern Hemisphere, especially at the higher latitudes. Higher latitude would be closer and closer to the North Pole.

Very large lakes are sometimes called inland seas. Some lakes completely dry up during parts of the year. They have water during rainy seasons or when snow melts.

Dams create man-made lakes when a river is blocked. These lakes are often called reservoirs.

Over 60% of the world's lakes are in Canada. There are 187,888 lakes in Finland, of which 60,000 are large.

Lakes that do not have an outlet or has water that evaporates rapidly tend to be salty. Examples are the Great Salt Lake in Utah, the Caspian Sea and the Dead Sea. The Great Salt Lake is saltier than the ocean. The Caspian Sea is the largest inland body of water on earth. It is about one-third as salty as the ocean. The Dead Sea is the lowest point on the earth's surface. Its water is 9 times as salty as the ocean.