In decentralized finance (DeFi), gas fees are used to compensate the network validators or miners for the computational resources required to process and validate transactions on the blockchain.

Gas fees are denominated in the native cryptocurrency of the blockchain network, such as Ethereum (ETH), and are typically paid by users when they execute smart contracts or perform other operations on the network, such as sending transactions.

In DeFi, gas fees play a critical role in ensuring the security and reliability of the network. By incentivizing validators to process transactions and execute smart contracts, gas fees help to ensure that the network remains decentralized and that transactions are processed in a timely and reliable manner.

Gas fees are determined by the current demand for network resources and are calculated based on the complexity and computational requirements of a given transaction. During periods of high network congestion, gas fees may rise significantly, making it more expensive to execute transactions on the network.

Therefore, DeFi users must carefully consider the gas fees when using DeFi protocols to ensure that they are not overpaying for their transactions. They can use various tools and services to estimate gas fees and optimize their transactions accordingly.