X-ray crystallography uses X-rays to determine the atomic structure of crystals. Crystals are bombarded with X-rays, which diffract upon contact with the atoms in the crystal. The angles and intensities of the diffracted X-rays are measured to deduce the positions of atoms in the crystal. This technique is useful for visualizing protein structures and identifying unknown crystal structures. It involves growing a crystal, exposing it to X-rays, and computationally analyzing the diffraction pattern to produce an atomic model of the crystal structure. X-ray crystallography has applications in characterizing polymers, assessing metal fatigue, and soil classification.