Barcode - What is a barcode?

Definition of BARCODE:

A representation of data that can be read by a machine; barcodes are either linear barcodes (one dimensional representations of data that are made up of a pattern of parallel lines and spaces) or matrix barcodes (two dimensional representations of data that are made up of a square or rectangular pattern (matrix) of black and white cells or modules – although other colours can be used).

Matrix barcodes are a newer form of barcodes and are able to represent more data per unit area; they are commonly used on small items or on surfaces where there is only a small area available for adding a barcode (although larger versions can be created). They are commonly used on small electronic components, food packaging, and are often printed onto labels to allow a variety of objects to be tracked. Perhaps the most well-known type of matrix barcode is the QR code, which has become extremely popular for use in marketing and promotional campaigns.

Linear barcodes are made up of a pattern of lines (known as bars and usually black in colour) and spaces (known as intercharacter gaps); they can be either “continuous codes” (the intercharacter gaps are part of the code) or “discrete codes” (the intercharacter gaps are not part of the code) and the bars can either run vertically (Picket Fence orientation) or horizontally (Step Ladder orientation). Data is represented by varying the width (and sometimes the height) and spacing between the bars; this data is most commonly a numerical code that will bring up a record or set of data/information when the barcode is scanned. For example, barcodes are commonly used to scan products at POS (point of sale), where the barcode will be used to bring up the product, pricing, and inventory information for that particular item.

Barcodes usually begin and end with a clear area or “quiet zone”, which is a blank space used to clearly indicate where the barcode begins and ends. The first and last characters in a barcode are known as the start character and stop character respectively; these characters provide the barcode reader with start and stop reading instructions and also indicate the orientation of the barcode. Some barcodes can be read successfully independently of the orientation (i.e. they can be scanned left to right or right to left) – these are known as bi-directional barcodes. The rest of the barcode will be made up of characters that represent the data that has been encoded into the barcode along with a check character or check digit that is used to perform a mathematical check to confirm that the barcode has been read correctly. The symbol density of a barcode refers to the number of data characters that can fit on a specific unit length and is usually expressed as the CPI (characters per inch).

While barcodes may represent a variable length code (the number of characters in the code can fit within a range), they are most commonly used to represent a fixed length code, such as a GTIN. GTIN stands for Global Trade Item Number and is a globally used standard for identifying trade items (products or services). The GTIN standard has incorporated a number of other standards (including International Standard Book Number (ISBN), International Standard Serial Number (ISSN), International Standard Music Number (ISMN), International Article Number (EAN), and some Universal Product Codes (UPC)) and may be 8, 12, 13, or 14 digits long. Usually, these standards are made up of a 2-3 digit number representing the country of origin (or language), followed by a manufacturer or company number, followed by product or item number, and ending with a check digit.

Barcodes are usually used to carry data that can be used to look up information about the item that the barcode is attached to, which makes them incredibly popular for use in the retail industry, where they can be used to look up product and pricing information at point of sale, to keep track of stock levels, to track and evaluate shopping habits, and to redeem coupons or vouchers. They can also be used in a variety of applications and environments to keep track of (and collate data about) people and items; for example, barcodes may be used on employee IDs to track work hours, are used on event tickets (for concerts, theatre performances, sporting events etc) to track admissions, can be used to track parcels and mail items, and are used to sort and direct airline luggage. They are commonly found in healthcare facilities and hospitals, where barcodes can be used on wristbands for patient identification, on surgical instrument kits to track equipment (and ensure sterilisation procedures are followed), to process medical samples for testing and track medical supplies (including blood infusions), and are used to improve the efficiency of medication management (including documenting the exact medications that are given to patients).

Barcodes are usually read by optical scanners called barcode readers or barcode scanners (although they can also be read using smartphone apps). Most of these devices work in the same way; light is directed at the barcode and the intensity of the light that is reflected back into the reader is converted into an electrical signal. The dark bars and light intercharacter gaps cause the intensity of the reflected light to fluctuate, which makes the electrical signal oscillate and form a pattern that can be converted into digital information and correlated to the database of information stored in a computer or device.

Barcode readers can be “Hand-Held” (small pen-like devices that can be moved over the barcode, often used by carriers to scan parcels), “Fixed-Beam” (slightly larger devices where the barcode is placed under a non-moving beam of light to be scanned), “Moving-Beam” (the devices move a beam of light back and forth in a straight line or X-shaped or star-shaped pattern, most commonly found in supermarkets and large retail POS), or “Video-Image” (a video signal of the barcode is taken and then decoded).

Here is the Harvard-style citation to use if you would like to reference this definition of the word barcode:
Label Planet (2016) What is a barcode? | Barcode Definition. Available at: https://www.labelplanet.co.uk/glossary/barcode/ (Accessed: January 1, 2024).