This page is a guide of computer keyboard key switch mechanisms.
Most keyboard key mechanism today use rubber dome. ⁖ basically all laptop keyboard and Microsoft Keyboard Gallery. Rubber dome type is cheap to make, but is not as good as other mechanisms that use spring, because the tactile feedback is not precise, kinda wobbly. Usually what made it worse is the cheap key housing that goes with it. (ever had squeaky keys that make ugly noises and sometimes stuck midway due to friction?)
Scissor-switch is found in laptop computers, starting around ≈2002. It is still rubber dome, but is enhanced by a scissor-like mechanism above the rubber membrance.
This is most famous as used by IBM Model M keyboard, and loved by many programing geeks.
You press the key, the spring compresses, then at some point, it can't take it anymore, then CLICK, it buckles, crumpling and gave up all resistance!
This tech is old. If you want the tactile feel of the click, you can get from keyboards that use “Cherry MX Blue” switch. But if you really want buckling-spring, you can buy it from Unicomp. See: IBM Model M keyboard, Unicomp
Cherry Corporation of Germany makes mechanical switches used in many high-end keyboards. Their switches are known as Cherry MX switches. There are several different models with different properties of feel. These models are color coded. They are:
The “no click” types are good for gaming when a key needs to be pressed repeatedly quickly. (⁖ firearm trigger)
The clicky types are good for intensive typing.
Another type of expensive switch is by capacitance. In particular, one made by Topre Corporation, of Japan.
Topre key switch as famously used in Happy Hacking Keyboard (only the “Professional” model), and μTRON Keyboard.
am not really sure how this switch works, but i have used one for a couple of years. It's excellent. See “Matias Tactile Pro 3.0” amazon This keyboard has strong presence in Mac community.
List of Keyboards with Mechanical Switch
Another issue commonly discussed with key mechanism is key ghosting and n-key rollover. Basically, it means how many keys can be pressed simultaneously. See: Keyboard Ghosting; How Many Keys Your Keyboard Can Take?.