Amazon began in 1995 selling books from Jeff Bezos' garage. It now operates sites in seven countries with over 9 million square feet of warehouse space across 21 fulfillment centers globally. The central Amazon data warehouse contains 28 servers with four CPUs each, running Oracle database software. Small sellers use Amazon Marketplace, zShops, and Auctions to sell new and used goods. Associates earn commissions by linking to Amazon products from their own websites. Amazon recommends products similar to search terms or past purchases and those bought by other customers with similar search or purchase histories.