Rare earth elements (or REEs) is a generic name for 17 metals widely used mostly in high-technology devices, such as mobile phones, laptops, flat screen televisions, hybrid car batteries, lasers, optics, and military equipment. New uses for these metals are being constantly found, but more on that later. Despite the name, these metals are not actually rare in nature. The name refers to the fact that they are rarely found in a pure form and are usually mixed with other minerals, which makes extraction complicated and costly. Further, mining and refining of rare earth metals is environmentally challenging, due to acidic and radioactive byproducts.