Glossary
Permit (EIP-2612)
An ERC-20 extension that lets a user authorize a spender via a signed message instead of an on-chain `approve` transaction — saving gas and enabling gas-less UX.
Vanilla ERC-20 needs two transactions to swap on a DEX: first an
approve granting the router an allowance, then the swap itself.
EIP-2612 ("permit") lets the user sign an off-chain message that the
router can submit alongside the swap, collapsing it into a single
transaction.
Permit is the foundation of gas-less and one-click DeFi UX. The newer Permit2 (Uniswap) generalizes it to any ERC-20 — even tokens that don't natively support EIP-2612 — by holding allowances in a shared contract.