The PDF417 barcode, a type of 2D barcode, was invented by Dr. Ynjiun P. Wang in 1991 and is known for its ability to encode large amounts of data securely and inexpensively. The "PDF" in PDF417 stands for Portable Data File, and the "417" signifies that each pattern in the code consists of 4 bars and spaces in a total of 17 units. This barcode can encode up to 1,850 text characters or 2,710 numeric characters, making it highly versatile for various applications. The compact version of PDF417, known as Truncated PDF417, is designed to take up less space without sacrificing much data capacity, which is particularly useful in situations where space is at a premium.

The design of PDF417 is quite intricate, consisting of stacked rows that form a grid of codes. Each row has a start and stop pattern, which helps barcode readers determine where each row begins and ends. The rows are then stacked to form the complete barcode. The compact version reduces the number of rows while still maintaining the integrity of the data encoded. PDF417 uses Reed-Solomon error correction, which allows for some degree of damage to the barcode without loss of data. This error correction capability is adjustable and can be set to different levels depending on the needs of the application.

PDF417 barcodes are used in a variety of settings, including transportation, identification cards, and inventory management. They are particularly prevalent in the transport sector for boarding passes, logistics tracking, and also in government-issued identification documents due to their high data capacity and reliability. The ability to encode large amounts of data, along with the error correction features, makes PDF417 a robust choice for applications that require the storage of significant information in a compact space.