About barcodes

Information and terminology


Barcodes are optical representations of data, optimized to be read by a machine. Think of barcodes as a simple language: in the same way that we have letters and words to communicate about objects or ideas, barcodes have colors and shapes to communicate numbers or letters to a computer. "Bar" refers to the original format of barcodes—groups of parallel lines (bars), wherein the data is encoded by differing widths and spacings. "Code" means that the information is not readily human-recognizable; it requires a barcode scanner connected to a computer to interpret the encoded data.


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Categories of Barcodes

The original first-generation barcodes are called one-dimensional (1D), or linear barcodes, because their data is only encoded along one axis. Later, these evolved into two-dimensional (2D), or matrix barcodes. 2D barcodes encode data alone two axes—horizontally and vertically—and therefore possess a higher data density than linear barcodes. Some two-dimensional barcodes also incorporate vertically stacked 1D codes, or use circular encoding methods. So-called "three-dimensional" (3D) barcodes may either refer to barcodes that utilize a multi-color palette to enable higher capacity data encoding (where the color depth of the code becomes the third axis), or to barcodes that are physically raised or embossed on a surface.

Barcode Terminology

  • Symbology: A barcode type is called a "symbology". There are many different and diverse symbologies, and each one has its own specification that defines how the barcode data is to be encoded or decoded.
  • Checksum / check digit: Many barcode symbologies allow or require a checksum to be calculated and appended to the data. This value is computed based on the information in the barcode, and is used by barcode readers/scanners to detect errors when reading data.
  • Continuous symbology: In a continuous linear symbology, each character begins with a bar and ends with a space (or vice versa), allowing characters to be strung together continuously.
  • Discrete symbology: In a discrete linear symbology, characters begin and end with bars. The space between characters is ignored by the scanner.

Uses for Barcodes

The most widely recognized use for barcodes (and the use for which they were originally created) is product labelling. Symbologies such as the UPC [Universal Product Code] are used extensively by department stores, grocery stores, and almost anywhere else that sells merchandise. Barcodes provide retailers with a fast and efficient means to track items, update inventories, and change prices, and also enhance the consumer experience by quickening transactions at the POS (or Point Of Sale). Before barcodes were invented, retailers had to remember each product's price and enter it manually into the cash register at checkout; now they can simply use a barcode reader connected to POS software to scan each item's barcode.

Barcodes are also widely used in medical and hospital settings due to the ease with which they can organize large quantities of data. They may be used to identify patients, transmit medical history, manage medication, and more.

Products and patients are not the only things barcodes can track: rental vehicles, employees, standard mail, parcels, tickets, and airline boarding passes/luggage are all examples of everday barcode uses that you are likely to encounter. Any application that requires efficient input of machine-readable data to track and organize objects may use barcodes.

A more recent development in barcode function is the use of 2D codes (especially QR Code) to embed a hyperlink to a website. These codes may be read by some types of cellphones equipped with barcode scanner apps. Depending on the type of phone or app you use—Android and iPhone being the most popular—the barcode will trigger your phone's browser to load a web page from the embedded hyperlink.

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Our barcode generator supports many different barcode symbologies, with more on the way. A brief overview of each one may be found below.

  • UPC-A: This is the standard Universal Product Code barcode symbology, and is applied to goods from manufacturers for in-store tracking. A UPC-A symbol is made up of 12 digits, including a check digit for error detection.
  • UPC-E: A condensed version of UPC-A. All UPC-E codes may be converted to UPC-A, but not vice-versa; there are special requirements for the format to work. A UPC-E symbol is made up of 8 digits, including a check digit for error detection.
  • EAN-13: A superset of UPC-A, developed for international use. It is made up of 13 digits, including a check digit for error detection. The first 2 or 3 digits are usually a country code.
  • EAN-8: A condensed code to compliment EAN-13. It is made up of 8 digits, including a check digit for error detection.
  • ISBN: Also know as "Bookland", this is a way to encode ISBN numbers from books in barcode form. It is an EAN-13 barcode beginning with 978, followed by the ISBN number (minus the last digit), and the EAN-13 check digit.
  • Add 2 or 5: This is a supplemental extension of UPC-A, UPC-E, EAN-13 and EAN-8 barcodes. The two-digit variety is used for magazine and newspaper issue numbers, whereas its five-digit couterpart is mainly used for a suggested retail price.
  • Standard 2 of 5: A discrete symbology deriving its name from the fact that each character is encoded via five bars, two of which are always wide. It may contain any number of digits, plus an optional check digit. It was mainly found on airline tickets and is somewhat outdated today.
  • Interleaved 2 of 5: The upgraded version of Standard 2 of 5, allowing greater data density. The characters are "interleaved" with each other, alternately using bars or spaces of varying widths to encode data, hence Interleaved 2 of 5 codes must have an even number of digits.
  • MSI Modified Plessey: Developed by the MSI Data Corporation, this is a continuous symbology that may contain any number of digits, plus several options for checksums. It was mainly used to label retail store shelves.
  • Code 128: A high-density alphanumeric symbology, widely used due to its versatile character set. Symbols may be encoded using three different codes, which can be changed via code control characters; you don't have to worry about this because our generator automatically calculates the most efficient encoding for you. Data may be any length, with a check digit appended to the symbol.
  • QR Code: A 2-dimensional matrix barcode widely used to encode URLs, email addresses, and coupon promotions. Data may be of practically any type, including numeric, alphanumeric, binary data, and Kanji.