Bar codes

Bar codes are used for a lot of purposes from product coding and inventory control to providing electronically-readable tags giving supplemental information such as web links related to a place or thing. The name tends to be used generically to cover all sorts of printed tags that can be read by machines, even if some don't actually have bars in them; they may have dots, squares, triangles, or other shapes instead. Some are "one-dimensional", read linearly; others are "two-dimensional" with a matrix of shapes. Some make use of color to distinguish elements, but most are monochrome and can be printed in any arbitrary color (usually black). A bar code format is known as a "symbology".

The 1979 comedy book The 80s: A Look Back, giving a fake "future history" of the 1980s, had fake bar codes (in a square format) on every page, parodying a belief that this sort of thing (proposed to be used in computer magazines to provide scannable program code) would go mainstream. The book also had an article "Adieu, Print" about the demise of print publishing, which was a few decades ahead of its time.

Point-of-purchase codes

 * EAN-2
 * EAN-5
 * EAN-8
 * EAN-13 (used in place of UPC internationally and on books and medicines in the USA)
 * EAN-14
 * JAN
 * UPC-A (Universal Product Code)
 * UPC-E (compact variety of UPC)

Postal codes

 * Australia Post standard customer barcode
 * CPC Binary
 * DAFT
 * Facing Identification Mark
 * Intelligent Mail barcode
 * Japanese postal barcode
 * KIX barcode
 * Korean Postal Authority Code
 * PLANET
 * PostBar
 * POSTNET
 * Royal Mail 4-State (RM4SCC)

General linear codes

 * Codabar
 * Code 11
 * Code 25
 * Code 39
 * Code 93
 * Code 128
 * DPD Barcode
 * DUN-14
 * GS1-128
 * GS1 DataBar
 * HIBC
 * Interleaved 2 of 5 (I 2/5)
 * MSI
 * Pharmacode
 * Plessey
 * Telepen

Stacked linear codes

 * Codablock F
 * Code 16K
 * Code 49
 * PDF417
 * MicroPDF417

Square/Rectangular codes

 * Aztec Code
 * Code 1 (1A through 1H)
 * Compact Matrix Code
 * CyberCode
 * DataGlyph
 * Data Matrix
 * Datastrip Code
 * Dot code (Olympus)
 * Dot Code A
 * EZcode
 * Grid Matrix Code
 * Han Xin Code
 * HD Barcode
 * INTACTA.CODE
 * JAGTAG
 * MaxiCode
 * mCode
 * MiniCode
 * QR code (Quick Response, used in marketing)
 * QuickMark Code
 * Secure Seal
 * Snowflake Code
 * SPARQCode
 * SuperCode
 * Trillcode
 * VeriCode
 * WaterCode

Circular codes

 * 3-DI
 * ShotCode

Other shapes

 * ArrayTag

Multicolor codes

 * ColorCode
 * Color Construct Code
 * High Capacity Color Barcode
 * HueCode
 * MMCC
 * UltraCode
 * UnisCode

Large-scale data storage codes

 * Optar
 * PaperDisk
 * PDMark

Other/Misc./Unknown

 * CP Code
 * d-touch
 * Flattermarken
 * Keurig 2.0
 * InterCode
 * Latent image barcode
 * SmartCode

Links and references

 * Barcode (Wikipedia)
 * Monmouthpedia, a Wikipedia project to put QR-coded signs all over the town of Monmouth, Wales linking to appropriate Wikipedia articles about local things
 * Obituary of inventor of bar code
 * Choosing the right barcode
 * Barcode scanning in emulated video games
 * Barcodes and the Mark of the Beast (yes, of course there's a conspiracy theory about barcodes!)