What is a QR Code?
A QR code is a two-dimensional barcode that stores information readable by a smartphone camera. Learn what QR codes are, how they work, and how to create one.
A QR code is a two-dimensional matrix barcode that stores information as a pattern of black and white squares. Unlike a traditional barcode (which only stores ~20 characters), a QR code can store up to 4,296 alphanumeric characters — including URLs, contact info, and text.
How QR Codes Work
A QR code encodes data using a grid of squares. When a smartphone camera scans the code, it reads the pattern and decodes the stored information. Key structural elements: • Finder patterns (3 corner squares) — help the scanner locate and orient the code • Alignment patterns — correct distortion • Data modules — store the actual content • Error correction — allows reading even if the code is partially damaged
What Can a QR Code Store?
QR codes can encode many types of data: • Website URLs (most common) • Plain text messages • Contact cards (vCard) • Wi-Fi credentials (SSID + password) • SMS messages • Email addresses • Calendar events • Payment information
QR Code Error Correction
QR codes have 4 error correction levels (L, M, Q, H) that allow the code to be read even if 7%–30% of it is damaged or obscured. This is why QR codes with logos in the center still work — the logo covers part of the data, but error correction recovers it.
Try it yourself
Generate a QR CodeAbout QR Codes
QR codes were invented in 1994 by Denso Wave (a Toyota subsidiary) to track vehicle parts. They became globally mainstream after smartphones added built-in QR scanning in 2017–2018. Today QR codes are used for payments, menus, tickets, and marketing worldwide.
FAQ
- What does QR stand for?
- QR stands for Quick Response. The name reflects that the code can be read quickly by a scanner.
- Why do QR codes with logos still work?
- QR codes have built-in error correction that can recover data even when part of the code is missing. A logo covers some data modules, but the error correction algorithm reconstructs the missing information.
- How much data can a QR code hold?
- A QR code can hold up to 4,296 alphanumeric characters, 7,089 numeric digits, or 2,953 bytes of binary data. In practice, URLs and short text are the most common uses.
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