What is a QR code?
A square pattern of black and white blocks that a phone camera can read in under a second — usually to open a link, but it can carry text, contact details, or WiFi credentials too.
Scan this — it's a real one
QR stands for "Quick Response" — the whole point of the format is that a camera can read it almost instantly, without lining it up carefully like an old barcode scanner.
A traditional barcode — the kind on a can of soup — only stores data in one direction, as a series of vertical lines of varying width. That gives it a fairly small ceiling on how much it can hold. A QR code stores data in two dimensions, as a grid of black and white squares, which means it can pack in dramatically more information in the same physical space. That's the entire reason it exists: Denso Wave, a Japanese automotive parts supplier, developed it in 1994 to track components through the manufacturing process faster than a standard barcode allowed.
Look closely at any QR code and you'll notice three of the four corners have a distinctive square-in-a-square marking, but the fourth doesn't. Those three squares are "finder patterns" — they're what let a scanner instantly figure out the code's orientation and boundaries, even if the phone is held at an angle or the code is upside down. Everything inside that boundary is the actual encoded data, packed in as a specific pattern of dark and light modules.
What most people actually experience, though, has nothing to do with any of that. You point a camera at the square, the phone recognises the pattern, decodes it in a fraction of a second, and shows you a link or a prompt to tap. Everything about finder patterns and error correction is invisible — which is exactly why the format won over regular barcodes for consumer use: it just works, without anyone needing to understand why.
What's actually inside one
A QR code can hold more than just a link
A URL / website
By far the most common. Opens a webpage directly in the phone's browser — a menu, a product page, a form.
Plain text
Just displays a block of text on screen. No link, no app opening — useful for instructions or a short message.
Contact details (vCard)
Name, phone, email, company — scanning prompts "Save contact" and it goes straight into the phone's address book.
WiFi credentials
Network name and password encoded together. Scanning it joins the network — no typing the password by hand.
A pre-filled email or SMS
Opens the phone's mail or messaging app with the recipient and even a subject line already filled in.
A phone number
Opens the dialler with the number already entered — one tap to call, nothing to type.
One more distinction worth knowing
Static vs. dynamic QR codes
A static QR code has its destination baked permanently into the pattern itself. Once it's printed, that's it — change your mind about the link, and you need an entirely new code.
A dynamic QR code instead encodes a short redirect URL that the creator controls behind the scenes. The printed code never changes, but where it sends people can be updated at any time — which is the entire premise behind Unqode SmartQR, and why it's worth reading further if you're printing a code onto anything that's expensive or slow to replace.
Read the full comparisonQuestions
Common questions about QR codes
Scanning itself is safe — it's the same as your phone reading a pattern and showing you a link, which you then choose whether to open. The actual risk is the same as clicking any link from an unknown source: don't scan codes from places you don't trust, and check the URL your phone shows you before opening it, especially if the code was on a sticker slapped over something else.
Now that you know how it works, make one
Free plan includes unlimited static QR codes and 3 dynamic ones — no credit card required.