QR Codes: A Complete Guide for 2026

QR codes (Quick Response codes) have become ubiquitous in modern life. From restaurant menus to payment systems, these two-dimensional barcodes bridge the physical and digital worlds.

What Is a QR Code?

A QR code is a two-dimensional barcode that stores information in a pattern of black and white squares. Unlike traditional barcodes that store data in one dimension, QR codes store data both horizontally and vertically, allowing them to hold significantly more information.

QR codes were invented in 1994 by Denso Wave, a subsidiary of Toyota, to track automotive parts during manufacturing. The format was made freely available, leading to widespread adoption.

How QR Codes Work

QR codes use a specific encoding system. The three large squares in the corners are position markers that help scanners identify and orient the code. Smaller alignment patterns help correct for distortion. Data is encoded in the remaining pattern of modules.

Error Correction

QR codes include built-in error correction using Reed-Solomon codes. This means a QR code can still be read even if part of it is damaged or obscured. There are four error correction levels: L (7%), M (15%), Q (25%), and H (30%), representing the percentage of data that can be recovered.

Types of QR Code Content

QR codes can encode various types of data including URLs, plain text, phone numbers, email addresses, WiFi credentials, contact cards (vCards), calendar events, geographic coordinates, and more. The scanner app determines how to handle the decoded content based on its format.

Best Practices

Ensure sufficient contrast between the QR code and its background. Test your QR codes with multiple scanning apps before printing. Include a call-to-action near the QR code telling people what they will find when they scan it. Use URL shorteners for long URLs to keep QR codes simpler and easier to scan.