A piece of land surrounded by water on all sides is known as an island. Greenland is the largest island in the world. An island may be formed because of tectonic activities such as folding, faulting, and volcanic activities. In India, some islands of the Andaman and Nicobar Islands are of volcanic origin, while the Lakshadweep Islands are formed of corals. Islands near the seashore have been formed by denudation of the landmass by sea waves.