Nanotubes are flat layers of graphite rolled into tubes. They can be single-walled or multi-walled, and have different configurations including armchair, zigzag, and chiral. Nanotubes have exceptional properties such as high tensile strength, elasticity, density, thermal and electrical conduction, and chemical inertness. Potential applications of nanotubes include using them to reinforce composites, in electrical fields, and in fuel cells.