Tb, or terbium, is a chemical element with the symbol Tb and atomic number 65. It is a silvery-gray metal that belongs to the lanthanide series of the periodic table. Tb is known for its magnetic properties and is often used in various applications, including green phosphors for color television screens and LED lights. Terbium is relatively rare in the Earth's crust and is usually found in minerals such as monazite and xenotime. It is primarily extracted through mining and chemical processes. Due to its unique properties, Tb plays a significant role in the development of advanced materials and technologies.