The online retailer does not only lead in terms of desktop retailing but has also taken to mobile commerce. Amazon Mobile is one of the most popular apps in the United States. The Amazon app via smartphone is also the second-most popular purchase channel of Amazon buyers in the United States.
Amazon also offers Amazon Prime, an annually paid membership offering free two-day shipping in the United States as well as discounted one-day shipping rates, which current users regard as one of the key reasons for subscribing to the service. Amazon Prime has since opened to other countries and has also expanded to offer instant streaming of selected movies and television shows through Amazon Instant Video and music. The average annual Amazon shopping expenditure of Amazon Prime members was found to be 1,300 U.S. dollars on the online shopping platform every year, compared to 700 U.S. dollars spending of non-Prime members. The most popular product categories of Amazon Prime shoppers in the United States were electronics and physical books, followed by e-books and personal care products.
The company also offers its own line of personal electronics, most importantly the Kindle electronics range. Originally offered as a basic e-reader, the Kindle has strongly influenced e-book sales. The current Kindle Fire tablet range has transformed into a line of devices that also enable the consumption of media within the Amazon ecosystem. According to a survey of Prime households, Amazon Prime Video was the most popular value-added digital service, followed by music and e-book rentals. As of end-2014, Amazon has also made headway into smart electronics with its smart speaker called Amazon Echo, which in turn connects to the voice-controlled personal assistant service Alexa. User satisfaction with Alexa was generally high.