The kinematic scattering theory illustrated in Chap. 1 holds only for crystals thinner than about 2 nm (Hoerni 1956). The general characteristics, such as the positions of Bragg beams, can be precisely determined by the kinematic theory. The intensity of each reflection, however, is largely affected by multiple scattering effects among existing beams, because the interaction between the electron and the crystal is so strong that multiple-scattering effects are unavoidable. Therefore quantitative data analysis has to be performed based on dynamic scattering calculations. For this reason, the present and following chapters are devoted to the dynamic scattering behavior of electrons.