By what method, the age of biological fossils can be decided?

The age of biological fossils such as dead animals, birds, plants and trees can be decided by a procedure called Carbon-14 dating. The accurate age of the fossils can be determined by estimating the levels of C-12 and C-14. The radioactive carbon C-14 which is present in every living being gradually decrease in its volume after the death of the organism. But no change can be noticed in the levels of C-12. Thus, carbon dating plays a vital role in fossil study.