 Since life first emerged on Earth, the diversity of living organisms has continuously evolved into a variety of species, reaching the complexity that we see today. What drives this massive variation? Exposure to ionizing radiation, which emanates naturally from the cosmos, from the sun, even from the Earth itself, causing living organisms to mutate. Most of these mutations will not survive, but in rare cases, beneficial mutations create novel varieties, enabling them to survive and thrive in a wide range of environments. Over the millennia, farmers have taken advantage of these naturally occurring mutations by selecting and propagating the most promising ones. Today, we no longer have to wait for nature. In the 1920s, when researchers discovered that artificial ionizing radiation was capable of inducing beneficial mutations, crop breeders were able to increase the frequency of spontaneous mutations. The age of crop mutation breeding was born. To induce desirable crop mutations, seeds or other plant materials are exposed to ionizing radiation. These seeds are then grown for two to four generations, until the new but rare mutant characteristic can be identified. Once identified, seeds from the selected plants are grown for yet more generations to develop uniform breeding material. Advanced mutant lines are then tested in the field, and if necessary, crossed with existing varieties to retain their agronomic traits, and then compared in national trials with existing varieties, before finally being officially licensed and released to the farmers. Mutation breeding has generated thousands of novel crop varieties in hundreds of crop species and billions of dollars in additional revenue, delivering higher yields, increased nutritional value, resilience to the effects of climate change, and tolerance to diseases. Mutation breeding is a fundamental and highly successful tool in the global efforts of agriculture to feed an ever-increasing and nutritionally demanding population.