Relative dating determines the order of past events without necessarily determining their absolute age. It involves analyzing the positions of rock layers and fossils. The law of superposition, which states that the oldest sedimentary rock layer is at the bottom and the youngest is at the top, is a key concept.
Absolute dating, on the other hand, provides numerical ages for rocks and events. A number of techniques for determining absolute age rely on the decay of radioactive isotopes within materials to calculate how much time has passed since their formation. Such techniques use sophisticated equipment and techniques.