Activated carbon is a highly porous material with a large internal surface area. It is produced by subjecting carbon-rich sources, such as coal, wood, or coconut shells, to a process called activation. Activated carbon can appear as a black, granular substance, a powder, or in other forms like pellets, cloth, or honeycomb structures. Its physical properties, such as pore size distribution, surface area, and density, can vary depending on the manufacturing process and intended application.