A tablet computer, or simply tablet, is a one-piece mobile computer. Devices typically offer a touch screen, with finger (or stylus) 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, hide able 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" (18 cm), differentiating themselves through size from functionally similar smart phones or personal digital assistants. (based on Wikipedia.com)