What Is a QR Code? Everything You Need to Know

QR codes (Quick Response codes) are two-dimensional barcodes that store information in a pattern of black and white squares. Originally invented in 1994 by Denso Wave for tracking automotive parts in Japan, QR codes have become ubiquitous in daily life.

How QR Codes Work

A QR code consists of several key components. The three large squares in the corners are finder patterns that help scanners detect and orient the code. The smaller square patterns are alignment patterns for correcting distortion. The actual data is encoded in the remaining area using a specific pattern of modules (the individual black and white squares).

Data Capacity

QR codes can store different types of data with varying capacities. For numeric data, a single QR code can hold up to 7,089 characters. For alphanumeric data, the limit is 4,296 characters. For binary data, it holds 2,953 bytes.

Error Correction

One of the most important features of QR codes is error correction. QR codes can still be read even when partially damaged or obscured. There are four error correction levels: L (7% recovery), M (15%), Q (25%), and H (30%). Higher error correction means less data capacity but more resilience.

Common Uses

QR codes are used for website URLs, WiFi sharing, contact information (vCards), payment systems, restaurant menus, event tickets, product packaging, and authentication. Their versatility and ease of use have made them an essential tool in both personal and business contexts.

QR Code vs Barcode

Traditional barcodes are one-dimensional and store data in varying line widths. They hold limited data (typically up to 25 characters). QR codes are two-dimensional, storing data both horizontally and vertically, which allows them to hold hundreds of times more information in a similar space.