Abstract: A removable or embedded back-side keyboard (hereinafter “keyboard”) for tablet computers and other transportable electronic devices (hereinafter “TD” or “tablet device”) is disclosed. The keyboard buttons are located on the back side of the TD, invisible for a user, in order to input information by fingers of both hands simultaneously when a user holds the keyboard in his/her hands without additional support. The device allows for a significantly increased speed of data input in the TD in comparison with other existing methods of information input, due to consideration of the anatomical structure of human hands and maximally facilitating adaptation to touch-typing, when a user doesn't see the keys.