Keyboard.
Keyboards came from mechanical typewriters that didn't even used electricity. Chirstopher Latham Sholes, the U.S. mechanical engeneer, patented the typewriter thatlooks like the keyboard we usually use nowadays.
Keyboard is a input device which means that using the keyboard you get information into your computer. The keys of the keyboard also called keycaps. They placed in the same pattern and same distance from each other on each and every keyboard.
Most keyboards have 80-100 keys. They divided in a few groups:

• Typing keys.
• A numeric keypad.
• Function keys.
• Control keys.

Keyboard is a lot like a miniature computer. It has its own prossesoor. A large part of the circuitry of the keyboard produced by the key matrix.
The way the keyboard works is that when you press the key, it presses switch. That produces the circuit and allows the small amount of current to get through. In the plain words it means that when you press the key it sends the electric signal to the prossesor and prossesor filters it. If you press and hold the key, then prossesor recognizes that as if you press the key several times.
Character map is located in the ROM, and it helps prossesor to difine the keys. For example when you tipe the letter f it turns out to be the small letter f, but if you press Shift with the f key it turns out to be the capital F. And the way it works is that prossesor kind of "cunsults" the ROM. Most of the keyboards have the same character map but however you can change it and sometimes it could be differnt.