Kilauea formed from the uprising of magma from deep within the surface of the Earth. Kilauea is categorized as a hotspot volcano, which is the most common type of volcano in the Hawaiian Islands. These volcanoes do not form along the boundaries of tectonic plates as do most other volcanoes on land, but they form instead from eruptions of magma in hotspots beneath the ocean surface.
Kilauea is the youngest and smallest of the chain of islands that create the Hawaiian Islands. This volcano, like others in the island chain, does not move. Despite being immobile, however, the Hawaiian Island volcanoes are not inactive. Hotspot volcanoes remain active for hundreds to thousands of years after their birth; these volcanoes continue to slowly grow in size, and they contain gases and chemicals in their cores that regularly interact to produce chemical and physical reactions, which generate heat and pressure. Hotspot volcanoes may form at any time; they may also erupt for hundreds of years after their generation. It takes awhile, but eventually the magma produced by hotspot volcanoes cools and ceases to flow; this generally happens when tectonic plates move away from hotspot volcanoes. Tectonic plates leave cooling hotspots to generate new hotspots elsewhere, and they may eventually create entire volcano chains.