Europium is a chemical element with the symbol Eu and atomic number 63. It is part of the lanthanide series, which consists of 15 metallic chemical elements. Europium is a rare earth metal that was discovered in 1890 by French chemist Eugène-Anatole Demarçay. It is used in various applications, including as a phosphor in fluorescent lamps, as a neutron absorber in nuclear reactors, and as a contrast agent in magnetic resonance imaging (MRI) machines. Europium is also used to make some specialized types of glass that can change color and is a very important element in the electronics industry.