A gas fee is the cost of executing a transaction or a smart contract on the Ethereum network. Gas fees are paid in Ether (ETH) and are used to compensate miners or validators for processing transactions and securing the network. High gas fees can deter small transactions and make certain Ethereum-based applications costly to use, especially during periods of network congestion. As Ethereum transitions to Ethereum 2.0 and introduces more scalability solutions, the hope is that gas fees will be reduced, making the network more user-friendly.