In contrast to other keyboards, themechanical keyboard uses a physical switch lying below the key. Thuswhen you press the key, you actually press the switch down. Thissends the signal to the PC that a user has pressed a particular key.Most of the keyboards used nowadays have three layers of plasticmembrane below the key. Thus every time the top and bottom layersconnect; an electric circuit gets closed so that the information issent to the PC. The middle membrane possesses holes where differentkeys are placed. On pressing the key, a dome-shaped piece of siliconeor rubber is pushed through the hole to connect both the top andbottom membranes. The functioning of keyboard is quite similar tokeypad on an oven. Many console gaming systems also use gamepads withrubber-dome system.
The rubber-dome keyboards are muchcheaper than mechanical keyboards and are great at resisting theliquid spills, yet they do not provide an effective feedback whenevera button is pressed. On the other hand, mechanical keyboards givegreat feedback.
One of the greatest features of a goodmechanical keyboard is N-Key Rollover. All the keyboards possessingthese features are capable of detecting each key press. This wouldensure that all the letters are being recorded on a single press ofkey.
In case, you connect your PC to USB,the maximum number of keys which can be recorded at a time is 6 whilein mechanical keyboards there is no such limit.