A bar code is a machine-readable series of bars and spaces which represents alpha-numeric data. Different bar code symbologies have been developed for particular applications. Some symbologies are only numeric data while others are alpha-numeric and may contain the full ASCII set. The most common bar code symbologies include Code 39, Code 128, Interleaved 2 of 5 and UPC

Code 39 Code 39 is the most widely used industrial linear symbology. It is used by the U.S. Department of Defense and the automobile industry. Universal Product Code A UPC-A is the standard for supermarkets and retail outlets throughout the United States. All codes for retail applications must be registered and assigned by the UCC (Uniform Code Council). UPC EAN UPC EAN (European Article Numbering) is the European equivalent of UPC-A. This symbology is also used in Japan (JAN). Interleaved 2 of 5 Interleaved 2 of 5 is primarily used for carton labeling. It is also widely used by the automobile industry. Codabar Codabar is used by libraries and also by Federal Express. Code 93 Code 93 is a compressed version of Code 39. It is used by many companies in space restrictive applications . Code 128 Code 128 is the most versatile symbology and is widely used by the United Parcel service. Postnet Postnet is used by the U.S. Post Office as a machine readable version of the ZIP code. OCR A OCR A (Optical Character Recognition) was the first attempt to automate a human readable font. OCR B OCR B offers more characters but is otherwise very similar to OCR A. MICR MICR is primarily used in check printing and is not read optically like other auto ID symbologies. It is printed in magnetic ink and read with a special reader.