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A square block of black and white cells with three large squares at its corners.
Also known as: Square barcode, Black and white square
A QR code is a two-dimensional barcode, not a symbol with a meaning: the three large corner squares are position markers that let a scanner find and orient the grid, and the content is whatever was encoded.
Encodes data as a two-dimensional grid of light and dark cells, readable by a camera from any rotation.
Contexts: Software
Carries three large concentric squares at three of its corners, which are position markers that let a scanner locate the grid and work out its orientation — not decoration and not part of the encoded data.
Contexts: Software
Has no meaning of its own: what it does depends entirely on what was encoded, which is why a code printed in a public place cannot be judged safe by looking at it.
Contexts: Software
Carries three large squares at three of its corners, and they are position-detection patterns: they let a scanner find the code and work out its orientation from any angle, which is why a QR code can be read upside down and at a slant when a barcode cannot. The smaller square near the fourth corner is an alignment pattern that corrects for curvature.
Contexts: Packaging, Public information, Software
Was designed in 1994 by Denso Wave for tracking vehicle parts in Japanese manufacturing, and its patent holder chose not to enforce it — which is the reason it, rather than any of the competing two-dimensional codes, is the one on the restaurant table.
A square filled with an irregular grid of small black and white cells, with three larger concentric black squares occupying the top-left, top-right and bottom-left corners.