Why use a QR code?

A QR code is worth using when it removes typing at a moment when typing is the obstacle: joining WiFi, paying at a counter, opening a menu, saving a contact. It is not worth using where a tappable link already exists, or where the audience is moving.

The honest case for QR codes

A QR code does exactly one thing well: it moves a string from a physical surface into a phone without anyone typing it. Every genuine use case is a version of that.

Strong cases:

Situation	What it replaces
Joining guest WiFi	Reading a 16-character password aloud
Paying at a counter	Typing an account number or handing over a card
Reading a menu	Reprinting when prices change
Saving a contact	Typing a name, number and email
Opening a specific product page in a shop	Searching and hoping
Confirming a specific asset in the field	Typing a serial number

Weak cases:

Situation	Why it fails
A code on a website	The user is already on a device; give them a link
A roadside billboard	Nobody scans while driving
A code with no stated reason	"Scan me" is not a reason
A code in an email	An email is already tappable
A code as the only route to essential information	Excludes anyone without a phone

What actually determines whether it works

In rough order of effect:

Dwell time. Is the person standing still? A code in a lift lobby beats one in a corridor by an order of magnitude.
A stated reason. "Scan for the wine list" beats "Scan me".
Size for the distance. Printed width should be at least the scanning distance divided by ten. Most codes are far too small.
What happens next. A slow or irrelevant landing page does not just waste that scan; it makes the person less likely to scan the next code they see.

What a QR code cannot do

It cannot track anyone by itself, cannot install anything, cannot dial or pay without confirmation, and cannot change what it points at once printed — unless it points at a redirect you control. Understanding those limits is what separates a code that works from one that is decoration.

FAQ

When is a QR code the wrong choice?

On a website, in an email, on anything moving, and anywhere the audience cannot stop. Also as the only route to essential information, because that excludes people without a phone or data.

What makes people actually scan a code?

Standing still, and a stated reason. Dwell time and a specific benefit outweigh every design decision, including the size and styling of the code itself.

Do QR codes track me?

A static QR code contains only text and cannot track anything. The website it opens can track you exactly as any website can, and a dynamic code's provider records every scan.

Are QR codes better than NFC?

They are cheaper, work on every phone with a camera, and can be printed on anything. NFC is faster and needs no camera, but requires a chip in every item and is not readable from a distance.