Freeganism is the practice of consuming food that has been thrown away by someone else (e.g. supermarkets) in order to minimize the destructive impact consumption has on the environment.

Acting in this way, a Freegan has little responsibility for the material, energy and resources used in the production process of the goods he consumes since the goods have already exited the production-consumption cycle of money exchanged for goods.

In most developed countries, the quality demands and hygiene standards of consumers are so high that many foods stay perfectly edible for long periods of time after their expiry or "best before" dates. Naturally, the best seasons for freeganism pertaining to food goods are autumn and spring, when waste bins remain at refrigerator temperatures.

Freeganism in itself does not mean a person is following a certain kind of dietary behavior, though it is common that freegans practice vegetarianism or veganism.

Many people practicing this diet have been forced into it simply by lacking the income necessary to purchase food normally, rather than making a conscious decision to sustain themselves by scavenging when other choices are available.

Freeganism is also used to describe people who are vegan, 'unless it's free.' Unlike the above, these people do not necessarily eat food that was already thrown away, but rather they eat non-vegan food that is offered to them, or that would otherwise be thrown away. However, they may often have the same motives, or they may simply be acquiescing to their friends, relatives, or coworkers attempts to feed them non-vegan food.