1. Geometry of Crystal Structures.- 2. The Nature of Diffraction.- 3. Properties of Radiation Useful for Studying the Structure of Materials.- 4. Recording the Diffraction Pattern.- 5. Crystal Symmetry and the Diffraction Pattern.- 6. Determination of Crystal Structures.- 7. What Else Can We Learn from a Diffraction Experiment Besides the Average Structure?.- 8. The Dynamical Theory of Diffraction.- Appendix A: Location of Useful Information in International Tables for Crystallography.- Appendix B: Crystallographic Classification of the 230 Space Groups.- Appendix C: Determination of the Power of the Direct Beam in X-ray Diffraction.- Method 1: Aluminum Powder.- Method 2: Polystyrene.- Method 3: Multiple Foils.- Method 4: The Ionization Chamber.- References.- Appendix D: Accuracy in Digital Counting.- D.1 Some Additional Information on Counting Electronics.- D.2 Measurement of Dead Time.- Answers to Selected Problems.