What Is a Barcode?

A barcode is a machine-readable pattern - classically a row of parallel lines of varying widths - that encodes an identifier a scanner can read in a fraction of a second. The crucial thing to understand is that the barcode itself carries almost no information: it holds a number, and the number is a key into a database where the real data lives - a product’s price, the stock count behind a SKU, or the owner and history behind an asset label.

How barcodes work

In a one-dimensional barcode, the widths of the dark bars and light gaps encode digits or characters according to a symbology - a published rulebook for translating stripes into data. A scanner shines light across the code, measures the pattern of reflections, and decodes it back into the identifier. Quiet zones (the blank margins either side) tell the scanner where the code starts and stops, and most symbologies include a check digit so a misread fails loudly instead of silently returning the wrong number.

Because the code is only a lookup key, the same physical label can mean different things in different systems - which is precisely why organisations that track individual items print their own labels rather than reusing whatever is on the box.

Types of barcodes

• EAN and UPC - the retail codes on consumer packaging worldwide, encoding a globally unique product number administered through the GS1 standards body. They identify a product type, not an individual unit.
• Code 128 - a compact, flexible format common in logistics and internal labelling; encodes letters as well as digits.
• Code 39 - an older alphanumeric format, less dense but very tolerant of cheap printing; long used for industrial and military labelling.
• ITF-14 - the heavy-duty format printed on shipping cartons.
• 2D matrix codes - QR codes and Data Matrix store data in two dimensions, hold far more (including full web links), and read from a phone camera. Strictly speaking these are barcodes too, just not made of bars.

The famous first retail scan - a pack of chewing gum through an American supermarket till in 1974 - was a UPC, and the same family of codes still runs retail half a century later.

Barcodes in inventory and asset tracking

In stock control, a barcode usually encodes the SKU, so a scan identifies which product is moving and the system adjusts the quantity. In asset tracking the requirement is different: a unique ID per individual item, because “a microphone” is not the same question as “which of our twelve microphones is this one”. The manufacturer’s packaging barcode cannot do that job - every identical unit carries the same code - so each item gets its own printed asset label, with the serial number recorded in the register alongside it for warranty and insurance purposes.

Barcode vs RFID and NFC

Barcodes are optical: they need line of sight, one scan at a time, but cost virtually nothing to print. RFID tags answer a radio reader without line of sight and in bulk - a doorway reader can inventory a whole trolley - at a real cost per tag and per reader. NFC is the short-range cousin built into phones, read by tapping rather than scanning. The honest summary: printed codes win on cost and simplicity, radio wins on speed at scale, and most small and mid-size operations never reach the scale where radio pays for itself.

Related terms

• Asset Label - the printed label that gives each individual item its own scannable ID
• SKU - the product-type identifier most retail and stock barcodes encode
• Serial Number - the manufacturer’s per-unit identifier, recorded alongside your own ID
• RFID - radio tags read at a distance, without line of sight
• NFC - tap-to-read radio identification built into modern phones