Aztec Code is a two-dimensional matrix symbology whose symbols are nominally square, made up of square modules on a square grid, with a square bullseye pattern at their centre. Aztec Code symbols can encode from small to large amounts of data with user-selected percentages of error correction.

Manufacturers of bar code equipment and users of the technology require publicly available standard symbology specifications to which they can refer when developing equipment and application standards. The publication of standardized symbology specifications is designed to achieve this.

ISO/IEC 24778:2008 defines the requirements for the Aztec Code symbology. It specifies the Aztec Code symbology characteristics including data character encodation, rules for error control encoding, the graphical symbol structure, symbol dimensions and print quality requirements, a reference decoding algorithm, and user-selectable application parameters.