X-ray crystallography is a powerfully important technique for the elucidation of protein structure, revealing the three-dimensional relationships of the atoms in a protein molecule. The first protein structure solved by x-ray crystallography was Sperm Whale myoglobin in 1958. Since that time, tens of thousands of protein structures have been successfully elucidated.

In X-ray crystallography, the interference pattern produced by X-rays reflecting off the closely spaced lattice of atoms in a crystal is recorded and then analyzed to reveal the nature of that lattice. The spacing in the crystal lattice can be determined using Bragg's law, which describes the relationship between the x-ray wavelength, lattice spacing, and the phase shifts corresponding to constructive interference.