A barcode is a pattern of dark and light elements - bars and spaces, or small squares - that represents data in a form a machine can read quickly and accurately. Scan it, and a number or text appears in the computer instantly, without anyone typing it.
Why barcodes matter
Typing a 13-digit product number by hand is slow, and people make mistakes. A barcode scanner reads the same number in a fraction of a second, with far fewer errors. That simple idea runs modern retail billing, warehouses, hospitals, courier networks, libraries, factories and jewellery stores. When you buy something at a supermarket, the price, stock level and sales report all start with one barcode scan.
What a barcode actually contains
Most retail barcodes do not contain the product name or price. They contain an identification number - for example a GTIN (Global Trade Item Number). The computer looks up that number in a database to find the name, price and stock. This is why the same barcode can show a new price tomorrow without reprinting the label.
Other barcodes carry more: a GS1-128 barcode on a carton can hold the product number, batch, expiry date and quantity; a QR code can hold a full web address, a vCard or a payment string.
Parts of a barcode
- Bars and spaces (or modules) - the pattern that encodes the data.
- Quiet zones - blank margins on both sides. If text or a box edge crowds them, scanners struggle.
- Start and stop patterns - tell the scanner where the code begins and ends, and in which direction it is being read.
- Check digit - a final digit calculated from the others, so the scanner can detect a bad read.
- Human-readable text - the digits printed under the bars, so a person can type them if the code is damaged.
- X-dimension - the width of the narrowest bar. It decides how big the barcode must be and which printer resolution you need.
How a scanner reads a barcode
A scanner lights up the code and measures the light reflected back. Dark bars absorb light; light spaces reflect it. Laser scanners sweep a red beam across 1D barcodes. Linear imagers take a one-line picture. 2D area imagers - now the most common - take a full picture, so they read 1D and 2D codes in any direction, and even barcodes on phone screens.
The decoder turns the pattern into characters and sends them to the computer, usually as if they had been typed on a keyboard.
1D and 2D barcodes
1D (linear) barcodes such as EAN-13 and Code 128 store data in the widths of vertical bars - typically up to a few dozen characters. 2D barcodes such as QR codes and Data Matrix store data in a grid of squares, so they hold far more (hundreds to a few thousand characters) in a smaller area, and can still be read when partly damaged. See types of barcodes for a full comparison.
What you need to use barcodes
- Numbers - for retail products, GS1 barcode numbers (barcode registration); for internal use, your own numbering.
- Labels - the right label material and size for the surface and environment.
- Printer and ribbon - a thermal barcode printer and, for thermal transfer labels, the matching ribbon.
- Software - label design software such as BarTender, or printing from your billing or ERP system.
- Scanners - handheld, fixed or mobile computers, connected to your software.
Mindware supplies all five - and makes the labels in-house in New Delhi.