In addition, Amazon sells many products from many different brands and companies. Customers are the most important to Amazon and Amazon knows that delivery service is one of the things customers want most. The way Amazon addresses customer satisfaction with its delivery service is by having 55 fulfillment centers located across North America. Since fulfillment centers are not retail stores, Amazon products are not required to charge sales tax. In addition to Amazon's 53 fulfillment centers in North America, Amazon also has 53 fulfillment centers in Europe, Japan, Asia and India. Since Amazon has many warehouses located in many different locations, it can reach its customers more easily. Amazon has grown over the years, which has allowed its business to reduce costs. In addition to being one of the best online shopping sites, Amazon also developed the Kindle, which is now one of the most popular tablet e-readers on the market.