A tablet computer, or simply tablet, is a one-piece mobile computer. Devices typically offer a touchscreen, with finger gestures acting as the primary means of control, though often supplemented by the use of one or more physical context sensitive buttons or the input from one or more accelerometers; an on-screen, hideable virtual keyboard is generally offered as the principal means of data input. Available in a variety of sizes, tablets customarily offer a screen diagonal greater than 7 inches, differentiating themselves through size from functionally similar smart phones or personal digital assistants. Though generally self-contained, a tablet computer may be connected to a physical keyboard, and a number of Hybrids that offer a detachable keyboard have been marketed since the mid-1990s, as have a number of convertible touchscreen notebook computers that offer an integrated keyboard that can be hidden by a swivel joint or slide joint, exposing only the screen for touch operation. Tablets have also appeared in a foldable Booklet format that offer the user dual-touchscreens, and can be used as a notebook by displaying a virtual keyboard on one of the displays. Via Wikipedia