A Data Matrix code is a two-dimensional matrix barcode consisting of black and white square modules arranged in either a square or rectangular pattern. The information to be encoded can be text or raw data. Usual data size is from a few bytes up to 2 kilobytes. The length of the encoded data depends on the symbol dimension used. Error correction codes are added to increase symbol strength: even if they are partially damaged, they can still be read. A Data Matrix symbol can store up to 2,335 alphanumeric characters.

Data Matrix symbols are square and made of cells, that is little squares that represent bits. Depending on the situation a white module is a 0 and a black module is a 1, or vice versa. Every Data Matrix is composed of at least two finder patterns or handles and two syncs. Handles are two perpendicular lines, coloured the same way as 1 modules, while syncs are like handles with the difference that they are made of alternating black and white modules. Handles achieve a good alignment with the symbol, while syncs sample modules correctly. If the matrix dimension grows, more syncs and handles are added up to 8 both horizontally and vertically. Symbol sizes vary from 8×8 to 144×144.

Source: Wikipedia