Cerium is a chemical element that belongs to the group of elements known as lanthanides. It has the symbol Ce and atomic number 58, meaning it has 58 protons in its nucleus. Cerium is a soft, silvery metal that easily oxidizes in air, forming a thin layer of cerium oxide on its surface. Cerium is one of the most abundant elements in the Earth’s crust and is used in a variety of applications, including automotive catalytic converters, as a polishing agent for glass and other metals, and as an alloying element in the production of magnets, aircraft engines, and other high-performance materials.