What is uranium dating?

Uranium dating is one of the ways of determining the age of ancient objects, even one million years old, by measuring how much of the following are present in them: the amount of radioactive isotopes of uranium, and the amount of other materials into which the radioactive isotopes would decompose. These measurements, when combined with knowledge about the initial state of matter under study (that is, composition at the time of death of an organism, or formation of a mineral) and the rate at which radioactivity takes place, would yield the age of the object.