There are several types of islands like continental islands and oceanic islands. Continental islands are found in shallow seas off large land masses. Greenland and Sri Lanka are examples of continental islands.
Oceanic islands are found out in the ocean. Most oceanic islands were created by volcanic activity, and are known as volcanic islands.
The majority of volcanic islands are found in the Pacific Ocean. The best example of such an island is Hawaii. In addition, there are also sedimentary and barrier islands. Sedimentary islands, like Friesan Island, are formed by the sediment that is deposited by rivers.
A barrier island is a long, thin, sandy stretch of land that runs parallel to the coastline. Long Island, New York, is a good example of a barrier island.
Finally, there are coral islands, such as the Maldives in the Indian Ocean. They are composed of the limey skeletons of microscopic creatures known as coral polyps.