White Castle is an American regional hamburger restaurant chain with 345 locations across 13 states, with its greatest presence in the Midwest and New York metropolitan area. Founded on September 13, 1921, in Wichita, Kansas, it has been generally credited as the world's first fast-food hamburger chain. It is known for its small, square hamburgers referred to as "sliders". The burgers were initially priced at five cents until 1929 and remained at 10 cents until 1949. In the 1940s, White Castle periodically ran promotional ads in local newspapers which contained coupons offering five burgers for ten cents, takeout only. In 2014, Time named the White Castle slider "The Most Influential Burger of All Time".

A hamburger, also called a burger, is a food consisting of fillings—usually a patty of ground meat, typically beef—placed inside a sliced bun or bread roll. The patties are often served with cheese, lettuce, tomato, onion, pickles, bacon or chilis with condiments such as ketchup, mustard, mayonnaise, relish or a "special sauce", often a variation of Thousand Island dressing and are frequently placed on sesame seed buns. A hamburger patty topped with cheese is called a cheeseburger.