Everything You Need to Know About QR Codes
From restaurant menus to marketing campaigns — how they work and how to use them.
How QR Codes Actually Work
A QR (Quick Response) code is a two-dimensional barcode that stores information in a pattern of black and white squares. Unlike traditional barcodes that only store data horizontally, QR codes store data both horizontally and vertically, allowing them to hold significantly more information — up to 4,296 alphanumeric characters.
The three large squares in the corners are position markers that help scanners orient the code regardless of angle. The smaller patterns encode error correction data, meaning a QR code can still be read even if up to 30% of it is damaged or obscured. This is why you sometimes see QR codes with logos in the centre — the error correction compensates for the missing data.
What QR Codes Can Contain
A QR code is just a container for text data. What makes them versatile is that phones interpret certain text patterns as actions. A URL opens in the browser. A "WIFI:" prefix auto-connects to a network. A "tel:" prefix initiates a phone call. You can encode plain text, URLs, phone numbers, email addresses, Wi-Fi credentials, calendar events, contact cards (vCard), geographic coordinates, and cryptocurrency addresses.
The most common use is simply encoding a URL. When someone scans the code, their phone opens the web page. This bridges the physical and digital worlds — see something in real life, scan it, and immediately access related online content.
Business Uses That Actually Work
Restaurant menus went digital during the pandemic and many never went back. A QR code on the table links to a web-based menu that can be updated instantly — no reprinting costs. Payment services like PayPal, Venmo, and bank apps use QR codes for peer-to-peer transfers. Marketing materials use QR codes to bridge print and digital — a poster can link to a video, a business card can link to a portfolio.
Event tickets increasingly use QR codes for entry — they are harder to forge than text-based codes and can be scanned quickly. Product packaging uses them for warranty registration, instruction manuals, or authenticity verification. Real estate agents put them on for-sale signs to link to property listings with full photo galleries.
Wi-Fi QR Codes: The Hidden Gem
One of the most useful QR code applications is sharing Wi-Fi credentials. Instead of dictating a complex password to guests, you can create a QR code that contains your network name, password, and encryption type. When scanned, the phone automatically connects — no typing required. This is particularly useful for businesses, Airbnbs, and offices with complex passwords.
The format is standardized: the QR code contains text in the pattern "WIFI:T:WPA;S:NetworkName;P:Password;;" and phones recognize this automatically. You can print it, stick it on the router, or frame it near the entrance.
Creating Effective QR Codes
Keep the encoded data short. Longer data creates denser codes with smaller modules (squares) that are harder to scan, especially from a distance or in poor lighting. Use a URL shortener if your link is long. Ensure sufficient contrast — black on white works best, though dark colours on light backgrounds work too. Never use light colours on light backgrounds.
Size matters: for a QR code scanned from 30cm away (like a business card), 2cm is sufficient. For a poster scanned from 2 metres away, you need at least 15cm. The general rule is the scanning distance divided by 10 equals the minimum QR code size. Always test your QR code on multiple devices before printing.
Security Awareness
QR codes can link to malicious websites just as easily as legitimate ones. Never scan random QR codes from stickers placed over original codes (a common scam at parking meters and restaurants). On most phones, the URL preview appears before opening — always check the domain before proceeding. Treat unknown QR codes with the same caution as unknown links in emails.