Barcode

A barcode is a machine-readable visual encoding of data — linear (one-dimensional, such as UPC or EAN) or matrix (two-dimensional, such as QR or DataMatrix codes). In a digital accessibility context, barcodes are commonly used as a lightweight way to attach identifying or descriptive data to physical objects so that blind or low-vision users can retrieve it through a camera-phone app that speaks the decoded content. Applications include grocery-product identification (via the UPC database), medication labelling, museum-exhibit audio descriptions, and printed materials that link to an accessible digital counterpart. Effective use depends on consistent placement, sufficient contrast, adequate physical size, and — critically — the user's ability to find the code in the first place, which often motivates accompanying tactile or fiducial markers.