A fast food restaurant, also known as a Quick Service Restaurant or QSR within the industry itself, is a specific type of restaurant characterized both by its fast food cuisine and by minimal table service. Food served in fast food restaurants typically caters to a "meat-sweet diet" and is offered from a limited menu; is cooked in bulk in advance and kept hot; is finished and packaged to order; and is usually available ready to take away, though seating may be provided. Fast food restaurants are usually part of a restaurant chain or franchise operation, which provisions standardized ingredients and/or partially prepared foods and supplies to each restaurant through controlled supply channels. The term "fast food" was recognized in a dictionary by Merriam–Webster in 1951.

Arguably the first fast food restaurants originated in the United States with A&W in 1916 and White Castle in 1921. Today, American-founded fast food chains such as McDonald's and KFC are multinational corporations with outlets across the globe.

Variations on the fast food restaurant concept include fast casual restaurants and catering trucks. Fast casual restaurants have higher sit-in ratios, and customers can sit and have their orders brought to them. Catering trucks often park just outside worksites and are popular with factory workers.