This brief review presents a comprehensive outline of the present research status on the fast moving carbon nanotube (CNT) field. It covers a short introduction to the relation between carbon nanotubes, graphite, and other forms of carbon and explains in detail the structure of CNTs. The electronic, electrical, and mechanical properties of CNTs, as well as the most widely used methods for CNT production such as electric arc discharge, laser ablation, and chemical vapor deposition (CVD), are discussed. Some of the CNT applications covered in this review article are: field emission, hydrogen storage, carbon nanotube-based solar cells, and CNT composite materials.