What is Protocol Fee?
A protocol fee is revenue collected by a DeFi protocol's smart contracts from user activity — such as trading fees, borrowing interest, or service charges — typically governed by token holders.
WHY IT MATTERS
Protocol fees are how DeFi protocols generate revenue. Uniswap charges 0.01-1% per swap. Aave takes a cut of borrower interest. Bridges charge crossing fees. These fees flow to the protocol treasury, liquidity providers, or token holders.
Fee switches — the ability to redirect fees from LPs to the protocol/token holders — are major governance decisions. Uniswap's fee switch has been debated extensively, as activating it could reduce LP incentives while creating protocol revenue.
Protocol fee revenue is increasingly used to evaluate DeFi projects. Revenue-generating protocols (fees > token emissions) are considered more sustainable than those dependent on inflationary incentives.