Using X-rays cristallography it is possible to visualize molecular structures. When an organic molecule in solution evaporate, a crystal deposit is formed. The crystals, lighted by an X-rays beam, produce a diffraction pattern which is used to reconstruct the structure of the molecule.
The source for X-rays is the synchrotron radiation produced by a particle accelerator.
A possible application of the study of protein 3D structure is the design of medications. The knowledge of the active zone of a molecule is used to synthetize an inhibitor. This inhibitor, penetrating the active zone, suppress the function and can for example kill a virus who need this particular function to survive.