Qr

QR stands for Quick Response. It is a type of two-dimensional barcode designed for high-density storage and fast decoding. QR codes were created in 1994 by Denso Wave, a subsidiary of Toyota, to track vehicles and parts during manufacturing. They have since become widely used in commerce and consumer applications. The format is standardized as ISO/IEC 18004.

A QR code is a square matrix of black modules on a white background. It includes finder patterns in three corners, a timing pattern, alignment patterns for larger sizes, and a data region that encodes information with error-correction codes based on Reed-Solomon. Data capacity and readability depend on version (1 to 40), error-correction level (L, M, Q, H), and the data type. QR supports numeric, alphanumeric, byte (binary), and Kanji encodings. Maximum capacity for version 40 with low error correction is up to about 7,089 numeric characters or 4,296 alphanumeric characters; byte mode holds about 2,953 bytes; Kanji about 1,817 characters.

Reading and creation: QR codes can be generated and scanned by cameras on smartphones and other devices; there are many libraries and apps. The format is widely used to encode URLs, contact information (vCard), Wi-Fi credentials, calendar events, and payments. It can also carry cryptographic signatures or short data payloads for authentication.

Security and limitations: QR codes themselves do not execute code; scanning can direct a user to malicious sites or prompt unsafe actions if not verified. Visual readability depends on contrast, printing quality, and damage tolerance is provided by error correction. Some privacy concerns relate to the ease of collecting scanned data.