Rollup
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.