An island is an area of ​​land (usually of natural origin) in the ocean, sea, lake or river, surrounded on all sides by water [1] and constantly rising above the water even during the period of the highest tide [2]. The islands differ from the mainlands by their smaller size [1].

The largest island in terms of area is considered to be Greenland, which is approximately three times smaller than the smallest continent - Australia. A group of offshore islands located close to each other is called an archipelago (for example, the Malay Archipelago). A series of small islands stretching in one direction is called a ridge (for example, the Kuril ridge).