The Transmission Electron Microscope (TEM) is the ultimate tool to see and measure structures on the nanoscale and to probe their elemental composition and electronic structure with sub-nanometer spatial resolution. Recent technological breakthroughs have revolutionized our understanding of materials via use of the TEM, and it promises to become a significant tool in understanding biological and biomolecular systems such as viruses and DNA molecules. This book is a practical guide for scientists who need to use the TEM as a tool to answer questions about physical and chemical phenomena on the nanoscale.