ZK-Rollup

A ZK-rollup is a Layer 2 network that processes transactions off-chain and submits a zero-knowledge validity proof to the base blockchain showing that the batch was executed correctly. Unlike an optimistic rollup, nothing has to be assumed and no challenge period is needed, so withdrawals to Layer 1 can settle much faster once a proof is verified. Generating these proofs is computationally heavy, which historically made ZK-rollups harder to build and to make fully compatible with Ethereum smart contracts. The trade-off is strong cryptographic assurance with low fees. Users should still note that funds move through bridge contracts, and that many ZK-rollups run centralised sequencers during their early stages.