Optimistic Rollup
A Layer 2 scaling solution that assumes transactions are valid and only runs computation if challenged.
In-Depth Explanation
Optimistic rollups (Arbitrum, Optimism, Base) post transaction data to L1 and assume validity. Anyone can submit a fraud proof during a challenge period (typically 7 days) if they detect invalid execution. This challenge period creates withdrawal delays—the main UX tradeoff versus ZK rollups. Optimistic rollups are simpler to build but slower to finality.
Related Terms
Rollup
An L2 scaling solution that executes transactions off-chain but posts transaction data or proofs to L1 for security.
Layer 2
L2Scaling solutions built on top of a base blockchain (L1) that process transactions off-chain while inheriting L1 security.
ZK Rollup
A Layer 2 scaling solution that uses zero-knowledge proofs to verify transaction validity without re-execution.
More in Infrastructure
View all →Gas Fees
Transaction fees paid to validators/miners for executing operations on a blockchain.
Gwei
A denomination of Ether equal to one billionth of an ETH, commonly used to express gas prices.
Layer 2
L2Scaling solutions built on top of a base blockchain (L1) that process transactions off-chain while inheriting L1 security.
Layer 1
L1The base blockchain that provides security and consensus, such as Ethereum, Bitcoin, or Solana.