A Layer-2 technique that executes transactions off-chain and posts compressed proofs or data to the base chain.
Rollups batch many transactions off-chain and submit either validity proofs (zk-rollups) or state roots with a dispute window (optimistic rollups) to the base chain. This reduces fees and increases throughput while inheriting base-layer security for final settlement.
"On an optimistic rollup, users transact cheaply off-chain, and the rollup posts periodic commitments to L1; if fraud is detected, challengers can prove it during the dispute period."
Trade-offs include data availability guarantees, operator centralization, and withdrawal delays (optimistic). zk-rollups offer fast finality but require complex proving systems.
"zk-rollups provide fast withdrawals but rely on expensive proving hardware; optimistic rollups are simpler but impose a challenge window before funds can exit to L1."
All terms and definitions may update as the Cryptionary improves.