Barcodes are a visual, machine readable representation of data which also often contain a human readable component. Traditional 1 dimensional types of barcode symbology are UPC / EAN, Code 39, Code 128, and Interleaved 2 of 5. Also frequently seen are 2D QR, DataMatrix variants and DiSa barcodes for authentication purposes.
Barcode labels are frequently used on secondary packaging or to cover up a previous barcode in the event of a misprint or change in data. In this instance, cover up material with opaque adhesive is used to insure the covered barcode is unable to be seen or scanned.
Due to their construction, points of data, and history, certain barcodes are ideally suited for specific industries.
UPC and EAN are often found on retail and consumer products.
Code 39 is used in the automotive industry.
Code 128 is used in logistics and shipping but not consumer facing products.
Interleaved 2 of 5 (ITF) is used in packaging.
QR Codes are used in retail and advertising.
DataMatrix codes are used to label retail and electronic products.
DiSa barcodes are used for asset protection on retail products.