The life of a farmer can be full of quick changes in fortune: Drought, blight, and other natural occurrences can change the financial outlook of a farm overnight. Banks, insurance, and other modern financial instruments are hugely important in smoothing out these ups and downs. But in the developing world, where farmers often don’t have access to financial institutions (if they even exist), life often means balancing on a razor’s edge. But farmers in Africa have a new tool to help them with their crops. They’re using their cell phones for banking services: making and receiving payments, and purchasing insurance. It’s a revolutionary use of technology that’s transforming how people in the developing world interact with money.