Describe the concept of gas in Ethereum.

Gas in Ethereum refers to a unit that measures the computational work required to execute operations on the Ethereum network. It serves as a critical mechanism that ensures the efficient functioning of smart contracts and transactions. Each operation or instruction has a predefined gas value, which reflects its complexity and the resources it consumes. When users initiate transactions or execute smart contracts, they must specify a gas limit and a gas price, which together determine how much they are willing to pay for the operations to be processed. This price incentivizes miners to include their transactions in the blockchain, as miners earn the gas fees for the work they perform in validating and executing them.

The concept of gas is vital for preventing abuse of the network by requiring that each computation consumes a certain amount of this resource. It also helps to maintain network stability and prioritize transactions based on the fees offered by users, allowing those willing to pay higher fees to have their transactions processed more quickly. This system plays a significant role in the overall functioning and economic model of Ethereum.