 users download from its App Store. Apple screens every application before it allows developers to sell apps in its online store. This control is one factor that has enabled Apple to maintain the high quality of its products. Apple is currently the leader in premium, high-end products. Its www.TechnicalPDF.com devices are priced at the high end of their respective market segments. Its high prices are a factor in Apple's enormous profits and market capitalization, the number of shares of stock outstanding multiplied by the current value of each share of stock. As of mid-2018, Apple's market capitalization was $1 trillion, the highest of any other company in the United States. Apple devices are based on proprietary operating systems and software. They are "closed" systems that require applications and printers that are compatible with Apple's operating systems. Customers who purchase its iPods often use Apple's iTunes store for music downloads. Compatibility between the applications in its App Store and the iTunes web site provides a compelling reason for customers to continue purchasing Apple gear SO that generally all-new apps are not needed for new mobile and wired computers. Apple's major innovation is its user-friendly interfaces, which have been a factor in the company's success since its inception, across all of its product lines. The emphasis on user-friendly interfaces was instituted by Steve Jobs, Apple's founder. Prior to its introduction of the iPad in 2010, only a small number of tablet computers were sold annually. In contrast, Apple sold 14 million iPads worldwide during the first year they were available because of the iPad's innovative, touch-screen interface. This spurred other manufacturers to introduce their own tablet computers and changed the way many people in business and homes use computers and watch video today. Apple introduced its iCloud music, photo sharing, and video storage service in 2011. Subscribers can access their music and video stored on iCloud from any mobile or wired computer