My name is randy what is your name
A bar code reader is an input Device. Although they sometimes output a visible light, the purpose is to gather data from a printed code and input that data into your system (computer, Point of Sale, etc.)
Input - the reader is reading the bar code and putting the information into the computer
your head
Different bar code readers can be installed using Google's Play Store. The store offers a wide range of bar code scanners such as "Bar code Scanner from ZXing Team or Google's own implementation of a qr/bar code reader : Google Goggles.
There are several companies that make hand held bar code readers. You can even get an app for your smart phone that will read bar codes. A major manufacturer of bar code reader is Motorola (they bought "Symbol" the leading bar code reader company a while back). Look at: http://www.motorola.com/Business/US-EN/Business+Product+and+Services/Bar+Code+Scanning
bar code reader
There's an app for that
There are numerous advantages to the use of a bar code. The primary two are speed and accuracy. A bar code reader can decipher the code in just thousandths of a second and transmit it with near perfect accuracy - much better than humans can.
Barcode Reader Because im guessing my answer
The bar code reader is used to read printed bar codes. It allows an attached computer to identify a product or item on which a bar code it printed and, most importantly, price that item to automate and speed checkout in a store or market.
A)mouseB)Barcode readerC)Optical Mark readerD) Printer
From the the user's point of view - the bar-code reader is much simpler to use. You simply point the reader at the bar-code - and it scans the sequence of black & white lines, sending data to a computer - which tells the user what the product is. With a keyboard, you would have to enter the long string of numbers printed under the bar-code - which not only takes more time - but could be entered wrongly.