A large landmass that is smaller than a continent is known as an island. Islands are often surrounded by water and can vary widely in size, from small islets to larger islands like those in the Caribbean. Islands can be formed through various geological processes, including volcanic activity, erosion, or sedimentation. They can also be categorized into different types, such as continental islands, which are connected to continental shelves, and oceanic islands, which arise from the ocean floor. Islands often hold unique ecosystems and biodiversity, making them significant for environmental studies and conservation efforts.