Blockchain

Blockchain records transaction data in sequential blocks, each containing the hash of the previous block. Altering past data breaks consistency with all subsequent blocks, making fraud immediately detectable.

Combined with QR codes, blockchain enables product authentication: scanning reveals manufacturing date, factory, and distribution route recorded on a tamper-evident ledger. What the chain protects is the record, not the label: a printed QR code can be photographed and reprinted, so a counterfeit carrying the copied code shows the same genuine history. Working as authentication therefore requires pairing it with first-scan detection per serial number or a cryptographic tag. Used for luxury goods, pharmaceuticals, and wine provenance.

As a distributed system, data is stored across many computers rather than a single server, providing high fault tolerance. Originally known as the foundation of Bitcoin, blockchain applications extend to logistics, healthcare, and government services.