Recall that atoms are the basic building blocks of matter.
Howstuffworks "How Carbon-14 Dating Works" radiocarbon WEB-info The method How accurate are Carbon-14 and other radioactive dating methods?
Other atoms are also named based on the number of protons they carry.
Notice in the diagram that eight different isotopes of Carbon are illustrated.
Three of the Carbon isotopes (C) are found in nature.
The rest of the carbon isotopes are only of laboratory interest.