Activated carbon is a term that includes a wide range of amorphous carbonaceous materials that exhibit a high degree of porosity and an extended interparticulate surface area. They are obtained by combustion, partial combustion, or thermal decomposition of a variety of carbonaceous substances. Activated carbons have been obtained in granular and powdered forms and are also being manufactured in spherical, fibrous, and cloth forms for some special applications. The granular form has a large internal surface area and small pores, while the finely divided powdered form is associated with larger pore diameters and a smaller internal surface area. Carbon cloth and fibrous activated carbons (activated carbon fibers) have a large surface area and contain a comparatively higher percentage of larger pores.