Gas refers to the fee required to successfully process a transaction or execute a contract on the Ethereum blockchain platform. Gas is literally the fuel of the Ethereum network.
Ethereum miners, who perform the important tasks of verifying and processing transactions, are awarded gas for their computational services. Gas measures the amount of work miners need to do in order to include transactions in a block. If a transaction needs to be confirmed as soon as possible, a higher gas price should be included with the transaction. If the gas price for a transaction is too low, miners can choose to ignore it.