Urbanisation is the large-scale movement of people from the countryside into towns and cities — the process through which modern societies ended up with most of their population living in urban areas. It transforms food systems profoundly: urban dwellers buy rather than grow their food, depend on long supply chains and processed products, and shift toward more meat, sugar, fat, and convenience foods — the nutrition transition that brings both undernutrition’s retreat and obesity’s advance. Feeding cities demands efficient logistics, cold chains, and wholesale markets, and it concentrates food waste and food-safety risks. Urban agriculture, from allotments to vertical farms, is a small counter-current. How cities eat is now one of the defining questions of global nutrition.