Gas Fee
The cost of executing an operation on Ethereum, priced in gwei.
Every Ethereum operation, from a simple transfer to a complex contract call, consumes a measured amount of gas. The user sets a price per unit in gwei, which is one billionth of an ether.
Since the EIP-1559 upgrade, part of every gas fee is burned rather than paid to validators, permanently removing ETH from supply when the network is busy.