Carbon nanotubes (CNTs), tubes of nanometer diameter, have exceptional properties and promising technological applications including in electronics. Different permutations and combination of mechanical, electrical, or chemical properties can be obtained by controlling the structure and surface chemistry and topography of these carbon-based nanomaterials. In this book, carbon nanotube materials, their range of properties from semiconductors, metals, and dielectrics, and fabrication methods, are introduced as well as their current and potential applications in electronics.