Long Island is an island in southeastern New York state, constituting a significant share of the New York metropolitan area in both population and land area. The island extends from New York Harbor 118 miles (190 km) eastward into the North Atlantic Ocean with a maximum north–south width of 23 miles (37 km). With a land area of 1,401 square miles (3,630 km2), it is the largest island in the contiguous United States.

An island or isle is a piece of subcontinental land completely surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. Sedimentary islands in the Ganges Delta are called chars. A grouping of geographically or geologically related islands, such as the Philippines, is referred to as an archipelago.