With thousands of food banks on six continents, there are many different models. However, there are some elements that food banks share.
There is typically one food bank in a city which runs a centralised warehouse. Like a blood bank, that warehouse serves as a single collection and distribution point for food donations. A food bank operates a lot like a for-profit food distributor, but in this case, it distributes food to charities, not to food retailers.
The largest portion of donated food comes from food left over from the normal processes of for-profit companies. This food can come from any part of the food chain, such as from growers who have produced too much or whose food is not visually appealing enough, from manufacturers who overproduced, or from retailers who over-ordered. Often, the product is approaching or past its "expiration", "sell by" or "best by" date. In such cases, the food bank works with food industry and regulators to make sure the food is safe and legal to distribute and eat.
Other sources of food include the general public in the form of food drives and government programmes that buy and distribute excess farm products mostly to help support higher commodity prices. Food banks can also buy food either at market prices from wholesalers and retailers at discounted prices, often at cost.
The food is then distributed to food aid agencies which could be private or public, religious or secular. The type and nature of the recipient agency varies depending upon the policies of the food bank, the nature of their community, and the laws of where they operate.