What Is a QR Code?

A QR code (Quick Response code) is a two-dimensional barcode that stores information as a pattern of black squares on a white grid. Unlike traditional barcodes that store data in a single line, QR codes store data in both horizontal and vertical directions, allowing them to hold significantly more information — up to 7,089 numeric characters or 4,296 alphanumeric characters.

How QR Codes Work

QR codes use a system of modules (small squares) arranged in a specific pattern. The three large squares in the corners are finder patterns that help scanners locate and orient the code. The remaining modules encode data using Reed-Solomon error correction, which allows the code to be read even if partially damaged or obscured. QR code readers — built into most modern smartphone cameras — decode the pattern and extract the stored information.

Common Uses of QR Codes

QR codes are used everywhere: linking to websites from print materials, sharing Wi-Fi passwords, mobile payment systems like Apple Pay and Google Pay, product packaging for additional information, event tickets and boarding passes, restaurant menus, contact sharing via vCards, and app download links. During the pandemic, QR codes became essential for contactless menus, check-in systems, and health information.

Generating QR Codes

You can generate QR codes for any text, URL, or data using online tools. Tool Elixir offers a free QR code generator that creates customizable QR codes entirely in your browser. You can control the size, error correction level, and content type. For developers, libraries like qrcode.js enable programmatic QR code generation.

QR Code Security

While QR codes are convenient, they can also be used maliciously. Bad actors can create QR codes that link to phishing sites or trigger malicious downloads. Always verify the destination before entering personal information after scanning a QR code from an untrusted source.