How Do QR Codes Work?

 The humble QR code often feels like a trend or an annoyance. But this technology, which is over 25 years old, is much more useful and brilliant than it seems. And once you learn how they work, you may find yourself generating QR codes and sticking them around your home!

Read more | Do QR codes expire?

What Is a QR Code?

The now-common QR code (short for “Quick Response” code) is a modern adaptation of the typical UPC barcode. It’s a machine-readable label that contains data, which a computer or smartphone can interpret faster than plain text or code.

Traditional UPC barcodes contain just twelve numbers, which may correspond to a grocery item or another product. But a QR code can store significantly more data—7,089 numbers, 4,296 letters, or 1,817 Japanese Kanji. You can use a QR code to store and recall website URLs, shipping information, automotive parts numbers, and other complex information.

But in most situations, QR codes are just shortcuts to websites or apps. A fast-casual restaurant may use QR codes to show customers its online menu, for example, while a clinic might ask patients to scan a QR code and fill out web-based paperwork.

How Do QR Codes Work?

To human eyes, QR codes look like a bunch of random pixels. But the QR code design is ingenious—not only does it contain a ton of data, but it’s purpose-built for quick, easy, and reliable scanning.

Notice the three large squares in the corners of a QR code. Computers use these squares to determine the code’s orientation, so even if you scan a QR code upside-down, it will work correctly. (When a QR code is “upright,” there isn’t a huge square in its bottom right corner.)

The pixels directly outside of these large squares indicate a QR code’s version number and, more importantly, its “format.” If you make a QR code to share your Wi-Fi login, for example, it will use formatting to tell phones or computers, “this is the name and password for an internet connection.”

And finally, there are the remaining pixels on a QR code. Some of these pixels are for error correction and “timing patterns,” which simply increase a QR code’s readability. But the bulk of these pixels represent raw data.

The data pixels on a QR code are clustered in small patterns, which communicate more information than simple black and white dots. And interestingly, this data is scanned both horizontally and vertically, which further increases data density. (Traditional barcodes are only scanned in one direction.)

Source | https://www.reviewgeek.com/131221/how-do-qr-codes-work/