An island is a landmass that is completely surrounded by water, defined by its isolation from continental landmasses. Geologically, islands can form through various processes, including volcanic activity, where magma cools above the ocean floor, or through the uplift of continental crust. Some islands are formed by the accumulation of coral reefs, while others may be remnants of larger landmasses separated by rising sea levels. The formation and subsequent evolution of islands are influenced by plate tectonics, ocean currents, and weathering processes, leading to diverse geographical formations ranging from high volcanic peaks to low-lying atolls.