Editing Introduction to keyboards (section)

==Inside the keyboard==
{{Main|Key|Keystroke sensing}}

It's unlikely that you've ever forced off one of the keys to see what's inside. However, sometimes a [[keycap]] (as it is termed) will ping off by accident and you get a brief glimpse as to what goes on inside the keyboard. Keycaps are removable (with care), and below the keycap on a modern PC keyboard you likely saw something like this:

<gallery widths=250 heights=187>
File:Dell KB522 -- dome and keycaps.jpg | Rubber dome in a [[Dell KB522]] keyboard
File:Dell KB522 -- stabiliser.jpg       | Rubber dome close up
</gallery>

It's a small dome made from silicone rubber. One such dome is found under each key. This design is frequently called "[[rubber dome]]" or "[[membrane]]" but the correct term is "[[rubber dome over membrane]]" because it uses a combination of rubber domes and membrane sheets to form a functioning keyboard. This cost-effective method for constructing keyboards goes back decades, and is now used almost exclusively in every desktop and notebook keyboard. Notebook keyboards use [[scissor switch]]es, which are an adaptation of this design for very thin keyboards.

<gallery widths=250 heights=187>
File:Apple MB110BA -- scissor switch.jpg | Scissor switch in an [[Apple Aluminium Keyboard]]
</gallery>

Pressing on a key squashes the rubber dome inside, and this presses together two membrane sheets (through a hole in a sheet in-between), causing electric current to travel through the key. This is then detected by the [[keyboard controller]]—a microchip inside the keyboard—and passed to the computer.

Rubber dome over membrane isn't perfect. The rubber changes its feel with age, either hardening or softening. The keys may get increasingly difficult to press, leading the operator to strike them with ever increasing force. They may instead gradually lose all feeling, until they are so limp that you can no longer feel what your fingers are doing. Particularly with scissor switches, the feel of keystrokes can be "gritty".

It will come as a surprise to learn just how many different ways there are to detect keystrokes. Scissor switches are bordering on silent, which to many is an advantage when many people are operating notebook computers in close proximity. Other methods can be very loud, often with the intention of being loud: the [[clicky|click]] sound generated by pressing a key is a clear audible indication to the operator that the keystroke was registered correctly.

Just as how you can choose a smaller keyboard to save space (or a larger keyboard to have extra keys to hand), choosing a different type of keyboard will change how it sounds and feels. More details on this subject follow below.