Crystallography is the study of the arrangement of the atoms in a solid material. Today, this term generally refers to methods that rely on the patterns of photons (commonly, X-rays), neutrons, or electrons that are diffracted after impacting a sample. The patterns of the diffracted radiation or particles can be interpreted to determine the structure inside the crystal. The interpretation of the diffraction patterns to yield a chemical structure is by no means a simple task, but crystallographers have been doing this for a long time and it has become a commonplace technique. Crystallographic methods have been used for decades to study the structures of inorganic solids and organometallic complexes.

We point out that, while crystallographic methods are commonly used to study inorganic compounds, they have also frequently been applied for studying other types of molecules as well, including biomolecules. While it can often be difficult to obtain a crystalline sample of a biomolecule, such as a protein, crystallography can be extremely useful in deducing protein structures.