In the third quarter of 2019, adjusted U.S. retail e-commerce sales amounted to over 154.54 billion U.S. dollars. Retail e-commerce sales in the United States are estimated from samples used for the Monthly Retail Trade Survey and exclude online travel services, ticket sales agencies and financial brokers. Online retail sales currently account for one tenth of total retail and approximately 5 percent of annual e-commerce revenue in the United States. The largest B2C e-commerce merchandise category is clothing and clothing accessories, including footwear. Online retail refers to customers buying goods or services from a seller online. Some online retailers are based on brick-and-mortar stores, whereas others are purely online retailing corporations. Most notable examples for online-based companies are market leaders Amazon and eBay. Prerequisites for online shopping are an internet connection and a valid method of payment. After purchasing, products are usually shipped to a designated address, picked up in-store or made available for digital distribution. Online retail provides 24 hours access to customers, as well as the possibility to shop around with ease and compare prices. Online retail sites often feature customer-written reviews in addition to the standard product information.