The touchscreen display is operated by gestures executed by finger or digital pen (stylus), instead of the mouse, touchpad, and keyboard of larger computers. Portable computers can be classified according to the presence and appearance of physical keyboards. Two species of tablet, the "slate" and "booklet", do not have physical keyboards and usually accept text and other input by use of a virtual keyboard shown on their touchscreen displays. To compensate for their lack of a physical keyboard, most tablets can connect to independent physical keyboards by Bluetooth or USB; 2-in-1 PCs have keyboards, distinct from tablets.