X-ray diffractionX-ray diffraction serves as the foundation for the science of crystallographyCrystallography. After the introduction of the unit cell concept in this chapter, the basis vectors in the space latticeLatticespace are defined, followed by the Miller indicesMiller indices that are used to identify atomic planesAtomic planes in the space lattice that serve to diffract the X-rays. Building upon the scattering theory introduced in Chap.  8 , the X-ray structure factor is introduced and used to draw the distinction between coherent and incoherent scattering. The reciprocal latticeLatticereciprocal, in which the scattering is analyzed, is then introduced, and its relation to the space latticeLatticespace is demonstrated. The von Laue[aut]Laue, Max conditions for constructive interferenceInterferenceconstructive of the scattered waves and[aut]Bragg, William Lawrence Bragg’s lawBragg’s law governing the angular dependence of the scattering are derived. As examples of the application of the above concepts, the structure factor is evaluated explicitly for the simple cubic, the body-centered cubic, and the face-centered cubic unit cells.