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"Wikipedia" encoded in Code 128-B

A barcode (also bar code) is a machine readable representation of information in the widths and spacings of printed parallel lines (or concentric circles, in at least one symbology). They can be read by optical scanners called barcode readers or scanned from an image by special software.

Table of contents
1 Applications
2 Symbologies
3 Types of barcodes
4 External links


Barcodes (and other machine readable tags like RFID) are used wherever physical objects need to be tagged with information that is to be processed by computers. Instead of painstakingly typing long strings of data into a terminal, the operator only has to display the code to a barcode reader. It also allows for processing without the help of human operators in fully automated environments.

The amount of data contained in a barcode varies with the application. In the simplest case only an identification number is provided which is used to index into a central database where the complete information is kept. The EAN-13 and UPC codes commonly found on retail articles work this way.

In many cases it is more desirable to include the complete information in the barcode itself without the requirement for an external database. This led to the development of barcode symbologies that can express more than decimal digits, ranging from additionally encoding just the upper case alphabet to the complete ASCII character set and beyond. The drive to encode ever more information in combination with the space requirements of simple barcodes led to the development of matrix codes which are often also named 2D barcodes, although most do not consist of bars but rather a grid of square cells.


The mapping between messages and barcodes is called a symbology. The specification of a symbology includes the encoding of the single digits/characters of the message as well as the start and stop markers into bars and space, the size of the quiet zone required to be before and after the barcode as well as the computation of a checksum.

Symbologies can be classified mainly by two properties:

Types of barcodes

Linear barcodes

PlesseyContinuousTwoCatalogs, store shelves, inventory
UPCContinuousManyUSA retail
EAN-UCC  Worldwide retail
CodabarDiscreteTwoLibraries, blood banks, airbills
Interleaved 2 of 5ContinuousTwoWholesale
Code 39DiscreteTwoVarious
Code 93ContinuousManyVarious
Code 128ContinuousManyVarious
Code 11DiscreteTwoTelephones
POSTNETContinuousTall/shortPost office

2-D barcodes

3-DIDeveloped by Lynn Ltd.
ArrayTagFrom ArrayTech Systems.
Aztec CodePublic domain.
Small Aztec Code 
BullseyeThis was the barcode tested in a Kroger store in Cincinnati. It used concentric bars.
CodablockStacked 1D barcodes.
Code 1Public domain.
Code 16KBased on 1D Code 128.
Code 49Stacked 1D barcodes from Intermec Corp.
CP CodeFrom CP Tron, Inc.
Data GlyphsFrom Xerox PARC.
Data MatrixFrom RVSI Acuity CiMatrix.
Datastrip CodeFrom Datastrip, Inc.
Dot Code A 
HueCodeFrom Robot Design Associates. Uses greyscale or colour.
INTACTA.CODEFrom INTACTA Technologies, Inc.
MaxiCodeUsed by United Parcel Service.
MiniCodeFrom Omniplanar, Inc.
PDF417The most common 2D barcode. Public domain.
Micro PDF417 
QR CodeFrom Nippondenso ID Systems. Public domain.
SmartCodeFrom InfoImaging Technologies.
Snowflake CodeFrom Marconi Data Systems, Inc.
SuperCodePublic domain.
UltraCodeBlack-and-white & colour versions. Public domain.

See also : Global Trade Item Numbering, RFID

External links