The C14 method or the carbon-14 method is a method of dating by measuring how much of the radioactive isotope C14 that is present in a sample. This means that only organic material that can be dated this way. Everything organic, whether it be plants or animals, incorporates carbon dioxide through the diet, among other, the radioactive isotope C14. When the tree, person, animal or grain dies, it stops exchanging carbon with its environment. The C14 isotope is unstable and from that point onwards the level of carbon begins to decrease. After 5730 years, only half the amount remains. By measuring how much C14 Is left in, for instance, a bone, it is possible to calculate when the owner of the bone died.