A Layer 2 blockchain for Ethereum. Launched in 2021, Optimism is an optimistic rollup chain, which accumulates transactions and summarizes them with a cryptographic proof on Ethereum. The "optimism" means that people are assumed to be honest, and the transactions can be challenged and widthdrawn within a certain time period. As one of the purposes of using a Layer 2 blockchain, Optimism executes transactions faster, and fees are lower than Ethereum. OP is the native token. See
Layer 2 blockchain.
Contrast with ZK
Optimistic rollups are generally contrasted with zero-knowledge proofs such as zkSNARK. See
zero-knowledge proof.