Radiometric dating, based on known rates of decay of radioactive isotopes in objects, allows a specific age of an object to be determined to some degree of accuracy.
The circumstances of the object may allow one to say that one object is older than another without being able to assign a particular age to the objects.
Absolute dating techniques determine how long before the present an event took place.
Relative dating techniques determine when events occurred in relation to one another.
Long Answer: Sciences such as geology, paleontology and archeology are very interested in identifying the age of objects found and these scientists sometimes use either relative dating or absolute dating to characterize the age of the objects they study.Before radiometric dating it was difficult to determine the actual age of an object.