Data Matrix Codes
A data matrix is a 2D matrix code, capable of encoding very large amounts of data in a compact space. It's used in a variety of capacities, including aerospace uses, component labeling, defense, mail, and printed media.
Specifications: A data matrix is capable of encoding up to 2,335 alphanumeric characters, or up to 3,116 numerical characters. It's composed of several blocks of black and white cells, that come in either a square pattern or a rectangular one. In addition, each data matrix has both a perimeter finder and a timing pattern. It can also encode symbols of various sizes, both large and small. Along the edges of each data matrix code is a quiet zone.
Advantages: A data matrix code is designed to be read even when it's up to 40% damaged, due to a built in error correction system. It's also capable of encoding either letters, numerical data, or other ASCII characters.
Disadvantages: Even though it can read a lot of characters, far more than most 1D barcodes, it still has an overall character limit, and so is impractical for sending longer messages.
Related Bar Codes:
QR - QR is also made up of blocks of black and white cells, along with finder patterns.