What is Gas?

Since each block has a limit to the amount of information it can contain, users must pay what is known as gas fees to miners/validators depending on the type of transaction they are attempting to execute. Simple transactions such as a transfer would use less gas and are thus cheaper than more complex actions such as a swap.

Gas fees are always paid in Ether. However, since transactions are in many orders smaller than a whole Ether, they are referred to in terms of Gwei. One Gwei is equivalent to 10^-9 Ether or 0.000000001 Ether.

It is good to think of gas as the fuel necessary to power a transaction. Gas is calculated for every computational step written in the code of a smart contract. By paying gas to complete a transaction, it effectively deters potential bad actors from abusing the system by overloading it with large number of transactions or spam.