The discovery of the Nanotube in 1991 by electron microscopy ha ushered in the era of Nanoscience. The atomic-resolution electron microscope has been a crucial tool in this effort. This book gives the basic theoretical background needed to understand how electron microscopes allow us to see atoms, togeher with highly practical advice for electron microscope operators. The book covers the usefulness of seeing atoms in the semiconductor industry, in materials science and condensed matter physics. Biologists have recently used the atomic-resolution electron microscope to obtain three-dimensional images of the Ribosome, work wihich is covered in this book. The book also shows how the ability to see atomic arrangements has helped us understand the properties of matter. This new third edition of the standard text retains the early sections on the fundamentals of electron optics, linear imaging theory with partial coherence and multiple-scattering theory. Also preserved are updated earlier sections on practical methods, with detailed step-by-step accounts of the procedures needed to obtain the highest quality images of the arrangement of atoms in thin crystals using a modern electron microscope. Sources of software for image interpretation and electron-optical design are also given.