So while something is living, they will have a certain amount of carbon-14 in their tissue. But then once they die, they're no longer adding more carbon-14. And the carbon-14 decays into the more stable carbon-12. And so based on the ratio between the carbon-14 to the carbon-12, and it takes roughly 5,000 years, 5,730 years to be exact, for roughly half of the carbon-14 to decay into carbon-12. So based on this ratio, and I go into much more detail in other videos, you can figure out how old these things are. And you get reasonably precise within a couple of hundreds of years. If you wanna go further into the past, there's things like potassium-argon dating, which is once again taking a radioactive form of potassium and using the idea that it decays into argon, and that when a volcano releases, the argon in that rock is able to go into the atmosphere, but then once it hardens, you have the decay.