Blockchain
An append-only, cryptographically chained ledger replicated across many parties — used in connected products mainly to anchor proofs of provenance and DPP records.
A blockchain is a sequence of blocks where each block hash-references the previous one, replicated across a network of nodes. The point is that no single party can rewrite history without every other node detecting it.
For SmartLinks-style connected products the blockchain is rarely the source of truth — that's the Product Record. Blockchains show up as anchors: a hash of a DPP version, a provenance event or an attestation is published on-chain so its existence and timestamp are independently verifiable later.
This 'anchoring' pattern gets you the integrity benefits without the cost, latency and privacy issues of pushing every product event on-chain.