XRD is a powerful technique to perform qualitative and quantitative analyses of materials and is most widely used for the identification of unknown crystalline materials. Determination of unknown solids is critical to studies in geology, environmental science, and material science to name but a few. When X-Rays contact a crystal, a series of reflections are produced that are unique and characteristic for each phase, similar to a fingerprint. It is a method that does not require large amounts of material, even very small amounts of material can be measured with special holders, and is non-destructive. This presentation will be focused on how XRD is used to measure materials from domestic and extraterrestrial sources.