Carbon-12 is a stable isotope of the element carbon, which is essential for life on Earth. It has six protons and six neutrons in its nucleus, giving it an atomic mass of approximately 12 atomic mass units. Carbon-12 makes up about 98.9% of all naturally occurring carbon, and it plays a crucial role in organic chemistry and biological processes. This isotope is significant in various scientific fields, including geology and archaeology, where it is used in radiocarbon dating. This method helps determine the age of ancient organic materials by measuring the ratio of carbon-14, a radioactive isotope, to carbon-12.