Even though QR codes were invented for industrial use, they’ve become a universal tool for quick, lightweight communication and information sharing, appearing everywhere from television commercials to video games. If you’ve ever wondered how QR codes work, where they came from, or how you can make your own, then this month’s Bits & Bytes is for you.
At their core, a Quick Response (QR) code is simply a two-dimensional barcode designed to hold more information than the regular striped barcodes we’re all familiar with. But instead of encoding data in a series of vertical lines, it uses a grid of black and white squares that can be read from any angle, even if part of the code is smudged or damaged.
The idea came from a Japanese engineer named Masahiro Hara, who worked at Denso Wave, a subsidiary of Toyota. In the early 1990s, Toyota’s factories needed a faster way to track parts moving along assembly lines. Traditional barcodes could only store a small amount of information and had to be scanned in a specific orientation. Hara and his team wanted something more flexible—something that could pack in more data and be scanned quickly from any direction. Their solution was the QR code, introduced in 1994. It was designed to be fast, robust, and easy for machines to read, but its usefulness eventually expanded far beyond manufacturing.
When you scan a QR code with a phone or a dedicated reader, the device interprets the pattern of squares using a set of rules defined by the QR standard developed by Denso Wave. The three larger squares in the corners act as orientation markers, helping the scanner figure out which way is “up." Smaller patterns throughout the grid handle timing, alignment, and, amazingly, even error correction; using a mathematical technique called Reed–Solomon error correction, a QR scanner can reconstruct missing or damaged data, allowing QR codes to function even if part of it is scratched, folded, or covered by a logo.
The amount of information a QR code can hold depends on its version and the type of data. A basic QR code might store a short URL, while more complex versions can store thousands of numeric characters. The most common everyday uses for QR codes are to point you quickly to a website, a menu, a payment page, or a downloadable file, but they’re also widely used in logistics, authentication, and marketing.
Not only are QR codes easy to use, they’re also exceedingly simple to create. You don’t need special hardware or programming knowledge to do so, as there are many websites and apps that let you type in text, a URL, or contact information and instantly generate a QR code for you. The generator arranges your data into the grid, applies error correction, and outputs an image you can save or print. If you want more control, you can use software libraries in languages like Python or JavaScript to generate QR codes programmatically. This is useful when you need to create many codes at once or embed them into a larger project. Regardless of the method, the underlying structure remains the same, and any modern device can read the result.
Unfortunately, as with most modern technology, even QR codes have the capacity for misuse. Next month, we’ll take a look at how scammers are taking advantage of them and how you can avoid falling prey to malicious QR codes.