Rollup
Last updated 17 October 2026Last verified 17 October 2026
What is a rollup in blockchain?
A Layer 2 that executes transactions off-chain and posts compressed data (and optionally validity proofs) to Ethereum. Optimistic rollups use fraud proofs and have a 7-day withdrawal delay; ZK rollups use validity proofs and can finalize faster. Both reduce fees by 10-100x while relying on Ethereum for ultimate security. See: No Blockchain, No AI.
TradFi equivalentBatching, not netting. Every transaction still executes and still settles gross, so nothing is offset. What is compressed is the data and the cost of verifying it, and on an optimistic rollup a balance is not immediately convertible at the base layer.