Transmission Electron Microscopy (TEM) is an advanced imaging technique used to observe the ultrastructure of specimens at a very high magnification. In TEM, a beam of electrons passes through a thin specimen, interacting with the sample to produce an image. This method allows for detailed examination of the internal structure of cells, tissues and even individual molecules. TEM operates on the principle of electron wave interference, which provides much higher resolution than light microscopy. This enables scientists to visualise fine details such as organelles within cells, virus particles and atomic arrangements in materials. Although TEM requires specialised equipment and preparation of ultra-thin samples, its ability to reveal intricate details at the nanoscale has made it essential in fields such as biology, materials science and nanotechnology. The book presents research and studies performed by experts across the globe. The various studies that are constantly contributing towards advancing technologies and evolution of this field are examined in detail. It is a vital tool for all researching and studying this field.