A device which is connected to a computer but not the part of core computer architecture is computer peripheral device. Core elements are like CPU, power supply, motherboard and the other computer cases. Mostly the term peripheral is used to refer a device which is external to a computer. By connecting device to a computer we are expanding system functionality. A printer is an example of peripheral device like once a printer is connected to a system you can printout your documents but the command to print the page is done via system only. So in that case we can say peripheral devices are dependent on computer systems.

Types of Peripheral devices

Peripheral devices are categorized into three categories:

Input Devices

• Keyboard: keyboard is very common input device which helps you to input data to computer. Layout is seems like a traditional typewriter having some keys and there functions. Some of the important keys are typing key these key include letters from A-Z and digits from 0-9, numeric keypad, functional key, control key and special purpose key.
• Mouse: Popular pointing device used for controlling the cursor having a small palm size box and a ball to scroll up and down. Basically it has two buttons left and right. Advantage is it is faster than arrow key of keyboard.
• Joystick: it is also known as pointing device which is used to move cursor position on monitor screen. Function is similar as mouse especially use for computer aided designing (CAD) and playing game in computer.
• Light pen: This device is similar to pen which is used to display menu items and draw pictures on monitor screen. A small tube of a pen consist photo cell and optical system.
• Scanner: it is work like a photocopy machine it is used when some information is available on paper and it to be transferred to a hard disc to manipulate data.
• Bar card reader: it is a device which is used to read bar coded data. This data is generally used for labelling goods, numbering the books etc.
• Optical mark reader: This is special type of optical scanner that recognize a mark made by pen or pencil. Used when you have to highlight few alternatives. Especially used for checking the marksheets.

Output Devices

• Monitors: Monitor as output device used for visual display unit we use this to view the work we are doing or we can also view finished product. Monitors comes in many size and that depends on your preference.
• Printers: printers are basically used for tangible products to look at away from monitors. For consumer use it comes in two types inkjet which use ink and sprayed on the print paper and another one is laser which uses heat technology and heat sealed on the paper.
• Plotters: This device draw pictures on paper based on commands from a computer. They are differ from printers in that sense they draw lines using pens and lines are continuous whereas printers simulates the lines with closely packed dots.
• Projectors: Projector is a device that takes images from the computers and display it on large screen which can be viewed by many persons in a hall.
• LCD projection panels: it is a type of video projector for displaying videos, images or computer data on the screen. It is modern and equivalent to overhead projectors.
• Speakers: It is the most common output device which is hooked up to any sound system. Primary focus is to produce audio that can be heard by listener regardless of design.

Storage Devices

Storage device is any computing hardware that is used for storing, porting and extracting data from files which store data temporarily and permanently.