Food security refers to reliable access to a sufficient quantity of affordable, nutritious food. Concerns over food security date back over 10,000 years when granaries were used to store food and distribute it during famines. Early definitions of food security focused on adequate global food supplies, but modern definitions also consider people's ability to access food. The 1996 World Food Summit defined food security as existing when all people have access to enough safe, nutritious food to live active, healthy lives.