Rare earth elements, also known as rare earth metals, are a group of 17 chemical elements with unique electronic, optical, and magnetic properties. These elements are considered rare because they are relatively scarce in the Earth's crust and are difficult to find in a concentrated form. Synonyms for rare earths include rare earth minerals, rare earth oxides, and rare earth metals. They are essential to the production of many high-tech products, including electronics, magnets, and batteries. The importance of rare earths in modern technology has led to concerns about their availability and the geopolitical implications of potential supply disruptions.