A buffet can be either a sideboard (a flat-topped piece of furniture with cupboards and drawers, used for storing crockery, glasses, and table linen) or a system of serving meals in which food is placed in a public area where the diners serve themselves. A form of service à la française, buffets are offered at various places including hotels, restaurants, and many social events. Buffet restaurants normally offer all-you-can-eat food for a set price, but some measure prices by weight or by number of dishes. Buffets usually have some hot dishes, so the term cold buffet (see Smörgåsbord) has been developed to describe formats lacking hot food. Hot or cold buffets usually involve dishware and utensils, but a finger buffet is an array of foods that are designed to be small and easily consumed only by hand, such as cupcakes, slices of pizza, foods on cocktail sticks, etc.

The essential feature of the various buffet formats is that the diners can directly view the food and immediately select which dishes they wish to consume, and usually also can decide how much food they take. Buffets are effective for serving large numbers of people at once, and are often seen in institutional settings, business conventions, or large parties.