The interaction of electrons with solids are briefly reviewed with the emphasis given to elastically and inelastically scattered electrons and the origin of characteristic X-rays, which are used for chemical analysis in electron microscopy. The physical origin of image diffraction and phase contrasts in the transmission electron microscope are discussed. Special attention is paid to the formation of Kikuchi line diffraction patterns. In scanning electron microscopy, Kikuchi lines are used for all orientation imaging techniques (OIM /EBSD) which allow us to determine the orientation of grains and to establish the presence of textures. In the case of transmission electron microscopy, Kikuchi line diffraction patterns are used as crystallographic maps which allow to orient single crystals. It will be explained how simple two beam diffraction contrasts can be obtained and a brief introduction into stereographic 3D methods in scanning and transmission electron microscopy will be given. The students will practice all the theoretical concepts themselves by performing exercises at a modern electron microscope.