Half life of carbon dating
Half-life is defined as the time it takes for one-half of a radioactive element to decay into a daughter isotope.
As radioactive isotopes of elements decay, they lose their radioactivity and become a brand new element known as a daughter isotope.
This technique relies on the property of half-life.
Let's say you found a fossil you think to be a human skeleton.
The best radioactive element to use to date human fossils is Carbon-14.
Different isotopes have different half-lives and sometimes more than one present isotope can be used to get an even more specific age of a fossil.
Below is a chart of commonly used radiometric isotopes, their half-lives, and the daughter isotopes they decay into.