Lanthanide compounds are chemical substances that contain elements from the lanthanide series, which includes 15 elements from lanthanum to lutetium. These compounds often exhibit unique optical and magnetic properties, making them valuable in various applications, such as in phosphors for lighting and displays, and in catalysts for chemical reactions. The lanthanides are known for their similar chemical behavior, typically forming +3 oxidation states. They can create a variety of compounds, including oxides, halides, and phosphates. Their compounds are also used in nuclear reactors and in the production of strong permanent magnets, highlighting their importance in modern technology.