Prove it's valid, instead of assuming it

A ZK (zero-knowledge) rollup takes the opposite approach from optimistic rollups: instead of assuming a batch is valid and waiting for a challenge, it generates a cryptographic validity proof for every batch. Ethereum verifies that proof in milliseconds, mathematically confirming the batch is correct before it's ever finalized.

Because there's no need for a challenge window, ZK rollups offer fast finality and near-instant withdrawals back to Ethereum, a real usability advantage over optimistic rollups' week-long wait.