Extraordinary chemical and physical properties of carbon nanotubes (CNTs) as well as the success of large-scale production by a catalytic chemical vapor deposition (CCVD) method, particularly with the use of a floating reactant technique, make them applicable in the fabrication of adsorbent, electrochemical electrode, and functional filler composite, etc at a possible low cost. Through judicious selection of transition metal, support materials and synthetic conditions (temperature, duration), it is possible to produce different types of CNTs such as multi-walled CNTs (MWCNTs), double-walled CNTs (DWCNTs)and single-walled CNTs (SWCNTs) selectively. In order to produce bulk quantities of CNT, a well-developed iron catalyst-based CCVD method so-called “Endo method" has been commonly used in the world. In this paper, we describe the synthetic techniques of various CNTs. The structural analysis will also be discussed in terms of nano-structure, and finally their practical applications of these CNTs will be described from the industrial point of view.