QR Codes Explained: What They Are and How to Use Them

What is a QR Code?

A QR code (Quick Response code) is a two-dimensional barcode that stores information as a matrix of black and white squares. Unlike traditional one-dimensional barcodes — which can only store about 20 characters — QR codes can store up to 4,296 alphanumeric characters in a compact square format that any smartphone camera can read instantly.

QR codes were invented in 1994 by Masahiro Hara, an engineer at the Japanese company Denso Wave (a Toyota subsidiary), originally to track automotive parts during manufacturing. Hara was inspired by the game of Go, which uses black and white stones on a grid — a visual similarity you can see in the structure of a QR code.

How Do QR Codes Work?

A QR code encodes data in the pattern of its black and white squares (called modules). The three large square patterns in the corners are finder patterns — they allow the scanner to locate, orient, and decode the QR code regardless of the angle at which it is held or photographed.

When you point your smartphone camera at a QR code, the camera identifies the finder patterns, determines the orientation and scale of the code, then reads the pattern of modules and decodes the binary data they represent. This entire process takes a fraction of a second on any modern device.

QR codes also include error correction — extra redundant data that allows the code to be read even if up to 30% of it is damaged, dirty, or obscured. This is why QR codes still work even when printed on textured surfaces, partially worn, or decorated with a logo in the center.

Types of QR Codes and What They Can Store

QR codes are not limited to storing website URLs. They can encode a wide variety of data types, each interpreted differently by the scanning device:

• URL / Website — The most common use. Opens a web page directly in the browser when scanned.
• Plain text — Displays a message or information on screen without any action.
• Email — Opens an email client with the recipient address pre-filled.
• Phone number — Initiates a phone call on mobile devices.
• SMS — Opens the messaging app with a pre-filled number and optional message text.
• WhatsApp — Opens a WhatsApp conversation with a specified number.
• WiFi credentials — Automatically connects the scanned device to a WiFi network without typing the password.
• vCard (contact) — Adds a contact card directly to the phone's address book.
• Geographic location — Opens a maps app with specific coordinates.

Practical Uses for QR Codes

For Businesses

Restaurants and cafés use QR codes on tables to link customers directly to digital menus, eliminating the need for printed menus that need constant updating. Hotels place QR codes in rooms linking to local guides, WiFi credentials, and service requests. Retail stores use QR codes on product packaging to link to detailed specifications, user manuals, or promotional landing pages.

Business cards with QR codes linking to a personal website, LinkedIn profile, or digital vCard make networking more efficient — a single scan shares all contact information without requiring the other person to type anything.

For Events

Event tickets are increasingly issued as QR codes — either printed or displayed on a smartphone screen. Venue staff scan them at the entrance for instant, forgery-resistant verification. Conference badges with QR codes allow attendees to share professional profiles and contact information with a single scan.

For Personal Use

A QR code for your home WiFi network, placed near the router or printed on a card, means guests can connect without asking for the password — and without you having to read out a long, complex password. A QR code on a homemade product or gift linking to a personal message or video is a thoughtful modern touch.

Static vs. Dynamic QR Codes

There are two main types of QR codes: static and dynamic.

Static QR codes encode the destination data directly into the code itself. Once created, the content cannot be changed — if the URL changes, you need to create a new QR code. Static codes are simple, free, and never expire because they do not rely on any third-party service. The WorldMerch QR generator creates static QR codes.

Dynamic QR codes store a short URL that redirects to the actual destination through a third-party service. The destination can be changed without replacing the QR code, and the service tracks scan statistics. Dynamic codes require a subscription to a QR management platform and depend on that platform remaining operational. If the service shuts down or your subscription lapses, all QR codes pointing through it will stop working.

For most personal and small business uses, static QR codes are the right choice — they are free, permanent, and require no ongoing service.

Best Practices for Printing QR Codes

• Size — Print QR codes at a minimum of 2 × 2 cm for close-range scanning. For wall posters or signs scanned from a distance, use at least 10 × 10 cm. As a rule of thumb, the minimum size is 10% of the expected scanning distance.
• Contrast — Always use dark modules on a light background. Avoid printing on colored backgrounds that reduce contrast. White space around the code (the quiet zone) is essential for reliable scanning.
• Test before printing in quantity — Always scan the final printed QR code from the expected distance before mass printing business cards, flyers, or packaging.
• Format — Download QR codes as SVG for print use — it scales to any size without losing quality. PNG is suitable for digital use and small print runs.