Explaining QR Codes

QR stands for Quick Response. The code was invented in 1994 by a Japanese company named Denso Wave, specifically two of their employees: Masahiro Hara and Takayuki Nagaya. Denso Wave was a subsidiary of Toyota. They originally designed it to track car parts during manufacturing. They needed something that could hold more information than a traditional barcode and could be read faster, even at weird angles.

Barcodes were cool and all, but they had one problem: they only store info in one direction—horizontally. QR codes fixed that by going two-dimensional. Instead of just stripes, they use both rows and columns of squares. Boom—more data, faster reads, and better error correction.

Denso Wave didn’t even patent it strictly. They allowed anyone to use it for free, which is one of the big reasons it blew up.

At its core, a QR code is just a square grid of black and white modules (fancy word for squares). These squares represent binary data—yep, just like the binary article I wrote. Black is 1, white is 0. That data is then translated into something useful, like a URL, a phone number, or a Wi-Fi password.

Parts of a QR Code

There are a few main parts of every QR code:

• Position markers (the big squares in 3 of the corners) — help the scanner figure out the orientation of the code.

• Alignment markers — help correct for distortion if the QR code is tilted or bent.

• Timing patterns — the striped lines along the edges that help keep everything spaced correctly.

• Format info — tells the scanner what error correction level is used.

• Data and error correction — the actual meat of the QR code.

Scanning

Here’s what happens when you scan a QR code with your phone:

1. Your camera sees the code and locates the position markers. That helps it know where the code starts and ends.

2. It reads the timing patterns to understand the spacing.

3. It decodes the binary data from the black and white modules.

4. Then it applies error correction (more on that in a bit).

5. Finally, it converts that binary into readable characters—like a web link—and shows it to you.

All of that happens in less than a second. Pretty cool.

Error Correction

QR codes are tough little guys. They can survive damage, dirt, and even having stickers or logos over them. That’s because they use a thing called Reed-Solomon error correction. Basically, the QR code stores some backup info alongside the real data.

There are four levels:

• L (Low) — recovers up to 7% damage

• M (Medium) — recovers up to 15%

• Q (Quartile) — recovers up to 25%

• H (High) — recovers up to 30%

That’s how it is possible some QR codes have logos or designs in the middle and still scan perfectly. The data is built to survive.

What do they do?

They’re not just for URLs! QR codes can hold:

• Text

• Contact info (vCards)

• Phone numbers

• SMS messages

• Calendar events

• Wi-Fi login credentials

• App download links

• Location coordinates

• Bitcoin addresses

And if you get fancy, you can even create dynamic QR codes. These don’t just store raw data—they point to a URL that can change later. This is useful for marketing or tracking scans.

Are they safe?

Mostly, yes—but be smart. QR codes can hide malicious links, just like any shortened URL. Don’t scan a sketchy code if you don’t trust where it came from. A QR code is just a door; what’s on the other side depends on who made it.

How are they made?

QR codes are generated by taking whatever data you want (like a URL) and encoding it into binary, then applying the QR code format rules. This includes the alignment patterns, error correction, and so on. The result is a grid of black and white squares. You can use tools online or even code your own generator in Python, JavaScript, or whatever language you like.

In Summary,

QR codes are everywhere for a reason. They’re fast, flexible, easy to scan, and can store way more data than old-school barcodes. Under the hood, it’s all just binary, alignment markers, and a little clever math. You can make them say anything—from a website to a secret emoji message.

Example:
Binary: 01001000 01101001
ASCII: H i
QR Code: Hi
I think that’s pretty awesome.