Food security is the state of having reliable access to a sufficient quantity of affordable, nutritious food. The availability of food for people of any class, gender or religion is another element of food security. Similarly, household food security is considered to exist when all the members of a family, at all times, have access to enough food for an active, healthy life. Individuals who are food-secure do not live in hunger or fear of starvation. Food security includes resilience to future disruptions of food supply. Such a disruption could occur due to various risk factors such as droughts and floods, shipping disruptions, fuel shortages, economic instability, and wars. Food insecurity is the opposite of food security: a state where there is only limited or uncertain availability of suitable food.

In politics, humanitarian aid, and the social sciences, hunger is defined as a condition in which a person does not have the physical or financial capability to eat sufficient food to meet basic nutritional needs for a sustained period. In the field of hunger relief, the term hunger is used in a sense that goes beyond the common desire for food that all humans experience, also known as an appetite. The most extreme form of hunger, when malnutrition is widespread, and when people have started dying of starvation through lack of access to sufficient, nutritious food, leads to a declaration of famine.