Gas is a unit that measures the computational effort required to perform certain operations on the Ethereum network. It represents the fee required for execution, regardless of the success or failure of the transaction.
Gas fees are paid in Ethereum’s native currency, Ether (ETH), expressed in units called gwei. 1 gwei is equal to 0.000000001 ETH, equivalent to 1,000,000,000 wei. Wei is the smallest unit of ETH, named after Wei Dai.