What exactly are Gas fees?
A transaction fee is roughly equal to the amount of Gas used × the Gas price. Gas prices are generally quoted in Gwei. If a transaction fails, the Gas used is generally not refunded because validators have already processed it.
Layer 2 bundles many transactions together before posting them back to the Ethereum mainnet, so the cost per transaction is usually much lower after it's split among them.
$ETH is the native token used to pay Gas fees on the Ethereum network.

#ETH

For reference only; make your own decisions before trading.