Both bar codes and Radio Frequency Identification tags can be used for similar purposes, but they are vastly different technologies. Essentially, bar codes are printed on labels and scanned by an optical bar code reader. Making bar code labels is inexpensive, but scanning them can be labor intensive. RFIDs use radio technology and can be programmed to convey a wide assortment of information to interact with RFID readers. They are more expensive to produce, but they can be used much more quickly.
A bar code is a series of vertical stripes printed on a label that is scanned by a bar code reader. Bar codes are most commonly used to track inventory by manufacturers, distributors and retailers. The width and position of the stripes determine the information that will be read by a bar code reader. Bar codes need to be on the outside of a product's packaging and are limited in the amount of information they can contain. For example, the bar code on a box of cereal identifies the product brand only. Every box of the same type has the same bar code. The bar codes do not contain dates or pricing information.
RFID tags are electronic devices that are manufactured and programmed rather than being printed on paper. They can be used to track inventory like bar codes do, but they can be scanned without being within the line of sight of a reader and are not limited to being scanned one at a time. RFIDs can contain much more information than a bar code. For example, an RFID beneath a pet's skin can provide a vet or animal shelter with the owner's name, telephone number and address. RFIDs are commonly used in items in stores in combination with an RFID gate at the door to detect attempts at theft.
Active and Passive RFIDs
RFIDs can be either active or passive. Active RFIDs are battery powered and emit a signal whether a reader is present or not. They can contain sensors to monitor motion, temperature or other conditions. They can initiate communication with a reader and can even be designed to interact with other RFIDs. Active RFIDs are used in hospitals, laboratories, auto manufacturing and on construction sites. Passive RFIDs have no internal power and require a reader to initiate communication. They are used in electronic tolls, bookstores, libraries and in the pharmaceutical industry.
Two-Dimensional Bar Codes
Two-dimensional bar codes, also known as matrix bar codes, are similar to UPC bar codes in that they are scanned by a line-of-sight reader. Two-dimensional bar codes consist of a white square background printed with small black squares, which can contain much more information than a one-dimensional UPC bar code. They are often used in advertising, such as magazine and newspaper ads, as well as on billboards and business cards. Scanning such a code with a smartphone application usually directs you to a business website. They are also known by the trademarked name QR Code or Quick Response Code -- a name given to them by the Japanese automotive company Denso Wave, which invented the codes in 1994.
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