Radiometric dating is a laboratory process that provides a numerical age for a rock or fossil. It must be completed in a laboratory because it is necessary to analyze the composition of the rock. Special atoms called parent and daughter isotopes present in the rock reveal the age of the rock. The parent isotope is unstable, and as a result, the isotope decays at a precise rate. As it decays, it produces a new, more stable material called the daughter isotope. Through analysis of a rock's composition, a scientist can compare the amount of parent isotope with daughter product and determine the absolute age of the rock.