Food is critical to good nutrition and health, but it is also essential to culture, society, tradition, religion, and individual values. Food systems consist of everybody and everything involved in bringing food from “farm to fork.” This chapter provides an overview of food systems and the key concepts necessary to understand how food systems function. Food systems consist of all the components and activities related to the production, processing, distribution, preparation, and consumption of food. Farmers and other food producers, consumers, businesses, civil society groups, and governments play major roles in the food system. Food system activities affect health and nutrition outcomes, as well as socio-economic status and the environment. Food supply chains, food environments, and consumer behavior represent three major components of food systems.