Metis is an Ethereum scaling solution (Layer-2) originally forked from Optimism. It provides support for multiple, interconnected L2 chains with main focus on supporting easy creation of DACs (Decentralized Autonomous Companies).
The Metis Layer 2 network assumes all transactions are valid until proven otherwise (“Optimistic Rollups”). These are called fraud proofs which are submitted in case the transactions are invalid. Validators post a bond, and this is slashed for invalid transactions. This is rigorously verified by Rangers who are financially incentivized auditors or validators – they will stake and mine Metis tokens by verifying transactions.