Total Value Locked (TVL) is the aggregate value of all assets — typically expressed in USD — that are currently deposited or locked in a DeFi protocol's smart contracts. TVL is the primary metric used to measure the size and adoption of DeFi protocols.

TVL is tracked by analytics platforms like DeFiLlama and is updated in real time based on on-chain data. It includes staked tokens, locked liquidity, lending deposits, and other protocol positions.

A growing TVL indicates increasing user trust and adoption. A declining TVL may indicate users withdrawing from the protocol. TVL is an imperfect metric — it can be inflated by token price increases rather than new deposits — but remains the most widely used measure of DeFi protocol activity.