Activated carbon is a material finding wide use in the environmental, industrial, and other fields for removal, recovery, separation, and modification of a variety of species in liquid‐ and gas‐phase applications. First, the historical development of activated carbon is briefly delineated. Then, the basic production principles of activated carbon from different types of raw materials by carbonization, thermal, and chemical activation procedures are discussed. Information is provided on various forms of activated carbon (powdered activated carbon (PAC), granular activated carbon (GAC), etc.). The physicochemical structure of activated carbon is discussed with regard to porous structure, surface area, and functional groups. The adsorptive, reductive, and catalytic properties of activated carbon as well as its synergistic effects in biological systems are delineated. Information is presented about the basic physicochemical and adsorptive parameters used for the characterization of activated carbon. Examples of various standards are given for testing and evaluating activated carbon. The applications of activated carbon in the treatment of drinking water, groundwater, municipal wastewater, industrial wastewater; remediation of contaminated groundwater and soil, air and gas cleaning, solvent recovery, and industrial production are outlined. Some special applications such as biogas purification and natural gas storage are also included. Information is provided on the handling and reactivation of spent activated carbon. A brief information is given about the evaluation of activated carbon by life‐cycle assessment. Finally, information is provided about worldwide production and prospects.