The fundamental principle behind carbon dating, also known as radiocarbon dating, is based on the decay of the radioactive isotope carbon-14. Living organisms continually incorporate carbon from the atmosphere, including a small percentage of carbon-14, which is stable while they are alive. When an organism dies, carbon-14 begins to decay at a known rate, allowing scientists to measure the remaining amount of this isotope in organic materials. This method enables the dating of archaeological and geological samples up to about 50,000 years old, providing insights into historical timelines.