X-ray Crystallography is a scientific technique used to determine the atomic and molecular structure of a crystal. When X-rays are directed at a crystal, they are scattered by the atoms within it, creating a pattern of spots on a detector. By analyzing this pattern, researchers can infer the arrangement of atoms in the crystal. This method is crucial in various fields, including chemistry, biology, and materials science. It has been instrumental in discovering the structures of important molecules, such as DNA and many proteins, aiding in the understanding of their functions and interactions.