Terbium is a chemical element with the symbol Tb and atomic number 65. It is a silvery-white rare earth metal that is malleable, ductile, and soft. Terbium belongs to the lanthanide series of elements, which are located in period 6 of the periodic table. It is a relatively abundant element and is found in minerals such as xenotime, euxenite, and gadolinite.

Terbium has a number of important uses due to its unique properties. One of the most important applications of terbium is in the production of green phosphors for fluorescent lamps and television tubes. These phosphors convert ultraviolet or blue light to green light and are used in many different types of devices that emit light, including traffic lights and smartphone screens.

Terbium is also used as a dopant in solid-state devices such as semiconductors, where it can help improve their properties. In addition, terbium is used in the nuclear industry as a neutron absorber and in the production of alloys that have improved magnetostrictive properties. Overall, terbium is an important and versatile element with a wide range of practical applications.