The book "Transmission Electron Microscopy and Diffractometry of Materials" offers a comprehensive introduction to the concepts of Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD), which are crucial for the characterization of materials. In its fourth edition, important new techniques in TEM are presented, including electron tomography, nanobeam diffraction, and geometric phase analysis. A new chapter on neutron scattering complements the topics of X-ray, electron, and neutron diffraction. All chapters have been updated and revised to enhance clarity. The book covers the fundamentals of wave interactions and wave functions with atoms in solids, as well as the differences and similarities in using X-rays, electrons, or neutrons for diffraction measurements. It addresses both practical and theoretical aspects, making it suitable for both beginners and advanced readers.