Barcode types can be categorized into three main groups: numeric, alpha-numeric, and two-dimensional. The first two types are considered one-dimensional and include only numbers or a combination of letters and numbers as well as bars of varying widths. The last type is most commonly seen as a QR code: a square or rectangular shape showing a combination of short lines and dots.
About one dozen symbologies exist within the numeric-only barcode category. The most popular is the UPC code, which is commonly found on many retail items and contains information such as the manufacturer and product identity. EAN codes are usually used at point-of-sale.
Industrial, interleaved, standard, and Code 11 barcodes are more popular within business and industry. They are often used in airline scanning, warehouse applications, telecommunications, and industrial settings.
POSTNET is a numeric system used by the U.S. postal service, and Codabar is used by FedEx and blood banks.
Fewer alpha-numeric codes exist with the primary one known as the Plessey code, which is used for grocery store shelf labeling and library coding.
The remainder of the symbologies within this category all originate from Code 39, which was the first alpha-numeric code created to be used in non-retail industries. LOGMARS, Code 93, and Code 128 are all used in defense and automotive industries.
This final category of barcodes became popular with the rising use of smart phones. These 2D barcodes allow the creator to encode more than 7,000 characters in one barcode.
When a 2D reader on a phone sees a barcode, it can transmit secure, encrypted data easily to the user.
Other two-dimensional codes include data matrix codes used in electronic and logistics, PDF417 codes used in transportation and inventory management, and Aztec used in travel industries.