Transmission Electron Microscope (TEM) is a very powerful tool for characterizing various types of materials. Using a light microscope, the imaging resolution is at several hundred nanometers, and for a Scanning Electron Microscope (SEM) at several nanometers. The imaging resolution of the TEM, however, can routinely reach several angstroms on a modem instrument. In addition, the TEM can also provide material structural information, since the electrons penetrate through the thin specimens, and chemical compositional information due to the strong electron-specimen atom interactions. This book provides a concise practical guide to the TEM user, starting from the beginner level, including upper-division undergraduates, graduates, researchers, and engineers, on how to learn TEM efficiently in a short period of time. Volume I covers the instrumentation, sample preparation, fundamental diffraction, imaging, analytical microscopy, and some newly developed microscopy techniques. This book may serve as a textbook for a TEM course or workshop, or a reference book for the TEM user to improve their TEM skills.