Carbon nanotubes are rolled-up sheets of graphene with a one-dimensional structure. The pioneering work on carbon nanotubes was first carried out by Prof. Iijima in 1991. Henceforth, carbon nanotubes have attracted significant attention from researchers because of their excellent physical, electronic, chemical, and mechanical properties. Carbon nanotube research, especially aiming at industrial applications is becoming more important, and it would be meaningful to summarize recent research topics as a book. This book presents the outstanding properties of these nanostructures along with their synthesis methods and their applications.