Every time you submit a transaction into any blockchain, it must be processed before being added to the blockchain. Each blockchain has a slightly different verification method, but all require time and energy. Because of this, they ask for a fee every time a transaction is sent, which is used to pay for the processing costs. This fee is known as a ‘gas fee’ since they ‘fuel’ the transaction, and without enough gas, a transaction will fail.

Depending on which chain you are working on, a different cryptocurrency will be used to pay for gas (for example, the Ethereum network will ask for ETH). Even if you are swapping assets other than this one, you will still need the native currency to pay for gas, which is why it’s always recommended to have some of it in your wallet to process transactions.

The actual monetary cost of gas for each blockchain is different. It can be affected by external factors such as the cost of the native cryptocurrency and network congestion. ParaSwap has no control over these and keeps none of the gas spent.

To add gas to a wallet, you can transfer it from another wallet or use an on-ramp to buy it using fiat currency like USD.