A tablet computer, or simply tablet, is a mobile computer with display, circuitry and battery in a single unit. Tablets are equipped with sensors, including cameras, microphone, accelerometer and touchscreen, with finger or stylus gestures replacing computer mouse and keyboard. Tablets may include physical buttons, e.g., to control basic features such as speaker volume and power and ports for network communications and to charge the battery. An on-screen, pop-up virtual keyboard is usually used for typing. Tablets are typically larger than smart phones or personal digital assistants at 7 inches (18 cm) or larger, measured diagonally.
Hybrids that include detachable keyboards have been sold since the mid-1990s. Convertible touchscreen notebook computers have an integrated keyboard that can be hidden by a swivel or slide joint. Booklet tablets have dual-touchscreens and can be used as a notebook by displaying a virtual keyboard on one of the displays.
Conceptualized in the mid-20th century and prototyped and developed in the last two decades of that century, the devices became popular in 2010.
As of March 2012, 31% of U.S. Internet users were reported to have a tablet, which was used mainly for viewing published content such as video and news. Among tablets available in 2012, the top-selling line of devices was Apple's iPad with 100 million sold by mid-October 2012 since its release in April 2010, followed by Amazon's Kindle Fire with 7 million, and Barnes & Noble's Nook with 5 million. As of May 2013, over 70% of mobile developers were targeting tablets (vs. 93% for smartphones and 18% for feature phones).