What Is a 1D Barcode?
A 1D barcode is the traditional single-row pattern of parallel black lines and white gaps you see on retail products, like a UPC or EAN code. It doesn't store any real content itself, it stores a short numeric ID that a scanner looks up in a database to retrieve the actual product information.
A 1D barcode encodes a short numeric string, usually a product number, by varying the width and spacing of a series of vertical black lines. A scanner shines a light across the pattern and reads the line widths in a single pass, left to right, translating them back into digits. Because the format only reads along one axis, there's no room to pack in more than about 20 to 25 characters before the barcode becomes impractically long.
The key thing to understand is that a 1D barcode doesn't contain the product name, price, or description. It contains an ID number, and that number only means something when a point-of-sale system or inventory database looks it up. Scan a can of soup and the barcode itself just says something like '0 51000 01251 6' — the register software is what turns that into 'Tomato Soup, $1.29'. Take the barcode away from the database it was designed for and it's meaningless on its own.
This lookup-key design has real limitations. The scanner needs a fairly direct, level angle to read the lines correctly, and a barcode with even a small tear or smudge across the lines often fails to scan entirely, because there's no redundancy built into the pattern to compensate for damage. Retail settled on 1D barcodes decades before smartphone cameras existed, when dedicated laser scanners were the only reader available, and the format has stayed essentially unchanged since.
QR codes solve a different problem. Instead of a numeric key into a database, a QR code can hold the actual content, a full URL, a block of text, contact details, right inside the pattern, and it can be read from any angle by an ordinary phone camera with no external lookup required. That's why QR codes replaced 1D barcodes for marketing, packaging call-to-actions, and anything meant to be scanned by the public rather than a store's checkout system, while 1D barcodes remain entrenched in retail supply chains where the infrastructure is already built around them.
This division of labor is unlikely to change soon, and it doesn't really need to — 1D barcodes are cheap to print, universally supported by existing retail scanner hardware, and well-suited to a closed system where a business controls both the code and the database behind it. QR codes solve a different problem: getting information directly into the hands of the general public without requiring them to have access to anyone's internal database at all.