Ethereum on Optimism

ETH, the gas coin of Optimism: every transaction here is paid for in ETH, with each fee covering the rollup's own execution plus the cost of publishing transaction data to Ethereum. ETH arrives through Optimism's canonical bridge, which locks it on Ethereum and credits it on Optimism, so a balance here is a claim on ETH held on the main chain. Optimism is an Ethereum layer 2 built on the OP Stack, open to the public since 2021.