This European Standard specifies the general principles of X-ray diffraction from polycrystalline and amorphous materials. This materials testing method has traditionally been referred to as “X-ray Powder Diffraction (XRPD)”, and is now applied to powders, bulk materials, thin film, and others. As the method can be used for various types of materials and to obtain a large variety of information, this standard reviews a large number of types of analysis but remains non-exhaustive.