A keyboard...

A Keyboard
The keyboard is the piece of computer hardware used to input text, characters, and other commands into a computer or similar device.
Even though the keyboard is an external
peripheral device in a desktop system (it sits outside the main computer housing ), or is "virtual" in a tablet PC, it is an essential part of the complete computer system.
Microsoft and Logitech are the probably the most popular physical keyboard manufacturers, but many other hardware makers also produce them.
Keyboard Physical Description
Modern computer keyboards were modeled after, and are still very similar to, classic typewriter keyboards. Many different keyboard layouts are available around the world (like Dvorak and
JCUKEN) but most keyboards are of the QWERTY type.
Most keyboards have numbers, letters, symbols, arrow keys, etc., but some also have a numeric keypad, additional functions like volume control, buttons to power down or sleep the device, or even a built-in trackball mouse that's intended to provide an easy way to use both the keyboard and the mouse without having to lift your hand off the keyboard.
Keyboard Connection Types
Many keyboards are wireless, communicating with the computer via Bluetooth or an RF receiver.
Wired keyboards connect to the motherboard via a USB cable, using the USB Type A connector . Older keyboards connect via a PS/2 connection. Keyboards on laptops are of course integrated, but technically would be considered "wired" since that's how they are connected to the computer.
Note: Both wireless and wired keyboards require a specific device driver in order to be used with the computer. Drivers for standard, non-advanced keyboards usually don't need to be downloaded because they're already included in the operating system . See How Do I Update Drivers in Windows? if you think you may need to install a keyboard driver but aren't sure how to do it.
Tablets, phones, and other computers with touch interfaces often don't include physical keyboards. However, most do have USB receptacles or wireless technologies which allow external keyboards to be attached.
Like tablets, most modern mobile phones utilize on-screen keyboards to maximize the screen size; the keyboard can be used when needed but then that same screen space can be used for other things like watching videos. If the phone does have a keyboard, it's sometimes a slide-out, hidden keyboard that rests behind the screen. This both maximizes available screen space as well as allows for a familiar physical keyboard.
Laptops and netbooks have integrated keyboards but, like tablets, can have external keyboards attached via USB.
Keyboard Shortcuts
Though most of us use a keyboard nearly every day, there are many keys you probably don't use, or at least aren't sure why you use them. Below are some examples of keyboard buttons that can be used together to form a new function.
Modifier Keys
Some keys you should become familiar with are called modifier keys. You'll probably see some of these in the troubleshooting guides here on my site; the Control, Shift, and Alt keys are modifier keys.
Mac keyboards use the Option and Command keys as modifier keys.
Unlike a normal key like a letter or a number, modifier keys modify the function of another key. The regular function of the 7 key, for example, is to input the number 7, but if you hold down the
Shift and 7 keys simultaneously, the ampersand (&) sign is produced.
Some of the effects of a modifier key can be seen on the keyboard as keys that have two actions, like the 7 key. Keys like this have two functions where the topmost action is "activated" with the Shift key.
Ctrl-C is a keyboard shortcut you're probably familiar with. It's used for copying something to the clipboard so that you can use the Ctrl-V combination to paste it.