Gas is the pricing mechanism employed on the Ethereum blockchain to successfully conduct transactions a contract. Activities that require gas include using smart contracts, launching decentralized applications (DApps) on the Ethereum network, and transactions like sending ETH between traders. The fee is basically the cost of running transactions paid by Ether (ETH).
Gas is consumed in small bits called gwei. One gwei is equal to 0.000000001 ETH. How much ETH is paid in a single transaction depends on the resources needed to carry a transaction on the EVM (Ethereum Virtual Machine) and Ethereum’s congestion level at the time of the transaction.
Gas can also be used to measure the time it takes for a transaction to be processed. The lower the price, the more time it takes to be processed because miners prioritize transactions with higher costs as it earns them more.