Carbon is an element.
Carbon ( from carbo `` coal '' ) is a chemical element with symbol C and atomic number 6 . Carbon is the 15th most abundant element in the Earth 's crust , and the fourth most abundant element in the universe by mass after hydrogen , helium , and oxygen . Carbon 's abundance , its unique diversity of organic compounds , and its unusual ability to form polymers at the temperatures commonly encountered on Earth enables this element to serve as a common element of all known life . It is the second most abundant element in the human body by mass ( about 18.5 % ) after oxygen . For this reason , carbon has often been referred to as the `` king of the elements '' .