A discount store or discounter offers a retail format in which products are sold at prices that are in principle lower than an actual or supposed "full retail price". Discounters rely on bulk purchasing and efficient distribution to keep down costs. Types (United States) Discount stores in the United States may be classified into different types: Hypermarkets (superstores) Discount superstores such as Walmart or Target sell general merchandise in a big-box store; many have a full grocery selection and are thus hypermarkets, though that term is not generally used in North America. In the 1960s and 1970s the term "discount department store" was used, and chains such as Kmart, Zodys and TG&Y billed themselves as such. The term "discount department store" or "off-price department store" is sometimes applied to big-box discount retailers of apparel and home goods, such as Ross Dress For Less, Marshalls, TJ Maxx, and Kohls. Category killers So-called category killer stores, specialize in one type of merchandise and sell it in big-box stores. Examples include: Apparel: Ross Dress For Less, Marshalls, Kohls, etc. Pet supplies: Petco, Petsmart Home furnishings and accessories: Big Lots, HomeGoods Office supplies: Staples, Office Depot, OfficeMax Warehouse clubs When membership is required, discount superstores are known as warehouse clubs, and often require purchases of larger sizes or quantities of goods than a regular superstore. The main national chains, both of which have operations outside the U.S., are Costco and Sam's Club. Discount grocery store Major discount grocery store retail chains in the U.S. include Aldi, Ingles, Lidl, Trader Joe's, Save-A-Lot and Grocery Outlet. Currently Aldi and Lidl are the largest discount retailers in the world operating more than 25,000 discount stores worldwide between them. Variety stores, dollar stores, five and dimes Variety stores in the U.S. today most commonly known as dollar stores such as Dollar General, Family Dollar and Dollar Tree, which sell goods usually only at a single price-point or multiples thereof (£1, $2, etc.). During the early and mid-twentieth century they were commonly known as "five and dimes" or "dime stores". Stores of the main chains, Woolworth's, J. J. Newberry and S. S. Kresge, lined the shopping streets of U.S. downtowns and suburbs, and starting in the 1950s they also opened branches in shopping malls. These chains originally sold items for 5, 10 or 25 cents, but many later moved to a model with flexible price points, with a variety