How does Carbon 14 Dating Work?

Carbon 14 dating works by comparing the amount of carbon 14 to carbon 12. There is a normal ratio of these two types of carbon in nature. When a fossil is made that ratio is locked into the fossil. But since carbon 14 is radioactive and decays, the ratio will change in the fossil over time. Since the half-life of carbon 14 is known scientists can figure out how old the fossil is.