The term "gas" refers to network fees on a blockchain network. Gas-fees often refer to the Ethereum network.
To execute a transaction, a fee must be paid. The gas-fee is the amount deducted from a transaction to process it. A transaction can be sending Ethereum or it can be executing a smart contract.
Ethereum (ETH) is the currency that "fuels" the Ethereum network, also called "ETH gas fee." Some actions that require more work, such as executing a smart contract, involve higher fees. Hence, transactions through the Ethereum network on a DEX (a decentralized exchange that runs on the blockchain) typically has a higher gas-fee than regular transactions.
When a transaction needs to be validated quickly, it is convenient to include a higher gas-fee. When the network is busy and many people want to send a transaction at the same time, gas prices rise due to demand. People then bid against each other to process the transaction faster resulting in a higher gas-fee.
Gwei is the unit used to indicate how much fuel it costs to perform a task. Because the gas-fee is made up of small numbers, it is usually expressed in "Gwei." A gwei is one billionth of one ETH (0.000000001 ETH). This is similar to "sats" in the case of Bitcoin.
