There are two main type of islands; continental islands and oceanic islands. Continental islands are part of a continental shelf. One example of this is Great Britain is an island that sits on the continental shelf of Europe. Oceanic islands are islands that don’t sit on a continental shelf. Many oceanic islands are formed by undersea volcanoes like Hawaii in the Pacific Ocean.
The term desert island is an island with no people on it. This does not mean that the island is a desert, but rather that it is deserted.
Around 1/6 people of the global population or 1,283,359,000 on the planet live on an island.