Keyboard Types

One factor determining the size of a keyboard is the presence of duplicate keys, such as a separate numeric keyboard, for convenience.

Further the keyboard size depends on the extent to which a system is used where a single action is produced by a combination of subsequent or simultaneous keystrokes (with modifier keys, see below), or multiple pressing of a single key. A keyboard with few keys is called a keypad. See also text entry interface.

Another factor determining the size of a keyboard is the size and spacing of the keys. Reduction is limited by the practical consideration that the keys must be large enough to be easily pressed by fingers. Alternatively a tool is used for pressing small keys.

Standard:

Standard alphanumeric keyboards have keys that are on three-quarter inch centers (0.750 inches, 19.05 mm), and have a key travel of at least 0.150 inches (3.81 mm). Desktop computer keyboards, such as the 101-key US traditional keyboards or the 104-key Windows keyboards, include alphabetic characters, punctuation symbols, numbers and a variety of function keys. The internationally common 102/105 key keyboards have a smaller left shift key and an additional key with some more symbols between that and the letter to its right (usually Z or Y). Also the enter key is usually shaped differently. Computer keyboards are similar to electric-typewriter keyboards but contain additional keys, such as the command or Windows keys.

Laptop-size

Keyboards on laptops and notebook computers usually have a shorter travel distance for the keystroke, shorter over travel distance, and a reduced set of keys. They may not have a numerical keypad, and the function keys may be placed in locations that differ from their placement on a standard, full-sized keyboard. The switch mechanism for a laptop keyboard is more likely to be a scissor switch than a rubber dome; this is opposite the trend for full-size keyboards.

Handheld

Handheld ergonomic keyboards are designed to be held like a game controller, and can be used as such, instead of laid out flat on top of a table surface. Typically handheld keyboards hold all the alphanumeric keys and symbols that a standard keyboard would have, yet only be accessed by pressing two sets of keys at once; one acting as a function key similar to a 'Shift' key that would allow for capital letters on a standard keyboard.^[1] Handheld keyboards allow the user the ability to move around a room or to lean back on a chair while also being able to type in front or away from the computer.^[2] Some variations of handheld ergonomic keyboards also include a trackball mouse that allow mouse movement and typing included in one handheld device..

Thumb-sized

Smaller external keyboards have been introduced for devices without a built-in keyboard, such as PDAs, and smartphones. Small keyboards are also useful where there is a limited workspace.