Potassium-argon dating is a method used by scientists to determine the age of rocks and minerals. It relies on the radioactive decay of potassium-40, a naturally occurring isotope of potassium, which transforms into argon-40 over time. By measuring the ratio of potassium to argon in a sample, researchers can calculate how long it has been since the rock or mineral solidified. This dating technique is particularly useful for dating ancient geological formations and volcanic rocks, often ranging from thousands to billions of years old. It helps scientists understand the timing of geological events and the history of the Earth.