Everybody has come across barcodes in their lives. It is a record of numbers, letters and special characters that are encoded with alternating black and white vertical lines. Their structure and structure is determined according to the accepted norms and principles of building a given code.

The codes are divided into the following categories:

a) due to the size of the code:

- one-dimensional (1D) codes - information is encoded using alternating black and white lines in one line, e.g. EAN-13 code or 128 code,

- two-dimensional matrix - information is encoded on a specific surface, usually by white and black squares or rectangles, e.g. QR code or DataMatrix code,

- two-dimensional two-dimensional codes - they are a variation of one-dimensional codes, they consist of several lines of code placed one below the other,

- complex - these are codes with a mixed structure, in which there are both 1D and 2D code elements,

b) due to the width of the lines:

- uniform - codes where all dashes are of the same width,

- non-uniform - codes in which the dashes have different widths,

c) due to the type of coded symbols:

- numeric codes - codes with only digits coded in the decimal system,

- alphanumeric codes - extension of numeric codes, in addition to numbers, various characters and symbols are encoded in them, e.g. letters, special characters, etc.

d) for the sake of code continuity:

- continuous codes - no gaps between coded characters,

- discrete codes - codes with gaps between coded characters,

e) due to the number of coded characters:

- fixed-length codes - codes where the number of coded characters is always the same, e.g. EAN-8 code,

- variable length codes - here the number of coded characters varies depending on the code type, e.g. code 128, interleaved code 2 of 5.