Geochronology is the science of determining the age of rocks, sediments, and fossils through various dating methods. It plays a crucial role in understanding the history of the Earth and the timing of geological events, such as volcanic eruptions and the formation of mountain ranges. By utilizing techniques like radiometric dating, scientists can measure the decay of radioactive isotopes in minerals to establish a timeline of geological processes. This information helps researchers piece together the Earth's history and understand the evolution of life over millions of years.