The invention provides a system and a method for data input that can be used with or incorporated into electronic, computer, and portable devices. The interface includes a small set of control buttons or keys that are used to provide access to an associated set of secondary keys, from which the user can select a character for input into the device. Intelligent ordering and grouping of the control and secondary keys allows the user to input information in a manner conducive to speed, accuracy, and ease of use, while the interface can be minimized to require less real estate than traditional keyboards. In accordance with one embodiment, a set of characters or symbols is divided into subsets, each subset being represented by a control button. Selecting a control button displays a secondary set of buttons representing actual characters or symbols that can be selected, stored, or displayed.