Keyboards are one type of computer input device.
Your computer, at its most basic level, communicates by sequences of different voltage amounts that translate to 1s and 0s, or binary code. Input devices allow you to communicate with the processor and operating system of your computer to produce a desired result, which is translated via electrical impulses into output that you can see and hear through your monitor and speakers. There are several types of input devices: keyboards, mice, image scanners and microphones.
Keyboards
Keyboards, the most basic form of input device, allow you to type alphanumeric or other symbols into a program. Two main keyboard layouts exist: QWERTY and DVORAK. The QWERTY layout, named for the first six keys on the top row of letters, is the standard keyboard layout for most computers. The DVORAK layout is different from the standard layout in that all vowels are on the home row.
Keyboards consist of an array of buttons, each of which when pushed, triggers a switch by closing a circuit, according to PC Tech Guide. The switch beneath each key on the keyboard transfers a signal to the keyboard controller that corresponds to the appropriate letter or number.
Mice
A mouse allows you to manipulate an onscreen cursor freely through two dimensions. Older models of computer mice consisted of a plastic shell that housed a ball that rolled simultaneously against two scroll wheels: one wheel controlled movement along the x-axis, and another controlled movement along the y-axis.
Optical mice operate by sending a red LED onto the desk surface or mousepad to reflect onto a miniature camera, recording the changing position of the mouse, according to Tech FAQ.
Scanners
A scanner allows a hard copy of a photograph or other document to be scanned and converted into an image file in Paint, Photoshop or a similar image manipulation program. The most common type of scanner is the flatbed scanner, which allows one page at a time to be scanned.
According to CompUSA, the scanner works by illuminating the image from the facing side as an array of semi-conducting capacitors scan the image. When the light particles contact the capacitors, electrons are released, allowing a charge to flow. When the scanner finishes analyzing the image, it sends information about the sequence of charges to your computer, which in turn converts the sequence to colored pixels, reproducing the hard copy as an image file.
Microphones
Microphones for a computer are used to record sound. When the air vibrations contact the diaphragm inside the microphone, the diaphragm creates an electrical signal to be converted and interpreted by your computer's sound card.
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