Radiocarbon dating work
Since it takes 5,568 years for an amount of 14 C to decay by 50 percent (half), if a specimen has one half the amount of 14 C as a modern piece of organic matter might have, we conclude it is about 5,568 years old.
Here's an analogy: Imagine you have a gallon of water to which you add one ounce of blue dye.
This means that things like stone, metal and pottery cannot usually be directly dated by this means unless there is some organic material embedded or left as a residue.
Once an organism dies the carbon is no longer replaced.
There are two techniques in measuring radiocarbon in samples—through radiometric dating and by Accelerator Mass Spectrometry (AMS).
The two techniques are used primarily in determining carbon 14 content of archaeological artifacts and geological samples.
Scientific American Editor Michael Moyer explains the process of radiocarbon dating.
Radiocarbon dating is one of the most widely used scientific dating methods in archaeology and environmental science.