Barcodes are machine-readable information that is usually represented as a 2-color (mainly black and white) graphic.

A distinction is made between so-called 1D barocdes, stacked barcodes and 2D barcodes.

1D barcodes consist of bars and gaps of different width and in different arrangement, which encode into certain information. Depending on the symbology, a different set of characters can be encoded. For example, with the symbology 2 out of 5 Interleaved, only pairs of digits can be encoded, while with Code 39, uppercase letters and some special characters can also be encoded. 1D barcodes encode the same information over the entire height. Their capacity reaches up to about 40 characters per barcode.

Stacked barcodes are barcodes consisting of several horizontally arranged elements, each element corresponding in structure to a 1D barcode. An example of a stacked barcode is the PDF417 barcode. Since this type of barcode, unlike 1D barcodes, does not encode the same information over the entire height, but different information per segment, its capacity is much higher than that of 1D barcodes and is several hundred characters.

2D barcodes are barcodes that encode the information 2-diminsional and have a high capacity of up to 3000 characters – depending on symbology and encoding type. The smallest elements of these barcodes correspond to bits from electronic data processing. The most popular 2D barcode at present is the QR code, which has found its way into almost all business sectors: Banking, insurance, travel, manufacturing, industry, etc. Other well known 2D barcode symbologies are Datamatrix and Aztec.

More information about the different barcode symbologies can be found here.