Overview
Optimistic rollups use a 'fraud-proof' mechanism. They post the results of transactions to the Layer 1 without proving their validity upfront, which makes them faster and cheaper to operate.
The Challenge Period
There is a window of time (usually 7 days) during which anyone can challenge the results of a batch by providing proof that a transaction was invalid. If a challenge is successful, the invalid transactions are rolled back.
Popular Examples
- Arbitrum
- Optimism