The carbon-14 isotope is important because it allows scientists to determine what about an organic sample?

It is through measuring the amount of carbon-14 in an organic sample that we can find out how long ago the sample was part of a living orgainsm.

Organic materials that have been preserved in some way can be dated using this technique, called radiocarbon dating. There are limits to how far back we can look with radiocarbon dating, but it is very helpful in a lot of cases were the age of the material goes back a few tens of thousands of years.