Costs that L2s pay to Ethereum for security

This page describes Onchain Costs, a tracker of the fees that Layer 2 networks pay to Ethereum for posting transaction data, proofs and state updates. The figures reflect costs borne by the L2 itself, not fees paid directly by users. Rollups periodically post state commitments to Ethereum, which are validated either by validity proofs or accepted optimistically and open to challenge through a fraud proof window. Because L2 data is also posted to Ethereum, the page states that no additional trust assumptions are introduced.