Costco is a membership-only retail warehouse club that sells products in bulk at low prices. It offers quality goods and services to consumers at the lowest possible prices using a membership and pricing strategy. Costco has grown significantly over the years, with the number of worldwide members increasing to over 100 million. It operates using a business model that relies on membership renewal and growth, bulk packaging and product samples, and guaranteed markups of no more than 15% to keep prices low.