A crystal is a solid material whose atoms are arranged in a highly ordered, repeating pattern. This structure gives crystals their unique shapes and properties, such as clarity and the ability to refract light. Common examples of crystals include quartz, diamond, and salt. Crystals can form through various processes, including cooling from a liquid or evaporating from a solution. They are found in nature and can also be created artificially. Crystals are used in many applications, including electronics, jewelry, and even in healing practices, where some believe they have special energies.