Radiocarbon dating and how it works
Radiocarbon measurements are always reported in terms of years `before present' (BP).
For example, if an object touches some organic material (like, say, your hand), it can test younger than it really is.
In 1960, he was awarded the Nobel Prize in Chemistry for this work.
He first demonstrated the accuracy of radiocarbon dating by accurately estimating the age of wood from an ancient Egyptian royal barge of which the age was known from historical documents.
Also, the larger the sample the better, although new techniques mean smaller samples can sometimes be tested more effectively.
The data can be a little off particularly in younger artifacts, and anything older than about 50,000 years is pretty much too old to be tested because at that point the majority of the C-14 has decayed to practically undetectable levels.