Gas is paid for exclusively in ether (ETH), the native cryptocurrency of Ethereum. While the amount of gas needed to execute a transaction on Ethereum is fixed, the conversion rate between gas and ETH is variable and set by the user. Users who set a higher gas rates and pay more ETH in gas fees are likely to get their transactions confirmed by the network faster than users who set lower gas rates. ETH spent by users to pay for gas on Ethereum is rewarded to miners, who are responsible for facilitating transactions and contributing computational energy, also called hashpower, to the network. Ethereum miners are soon to be replaced by validators through a forthcoming hard fork upgrade known as the Merge.
When the network is congested, users pay high fees for gas. Network congestion and exorbitant gas fees are driving users and developers to newer, less expensive networks. Ethereum is working to respond to scalability concerns by relying on Layer-2 network and rollup technology.