On the ethereum blockchain, gas refers to the cost necessary to perform a transaction on the network. Miners set the price of gas based on supply and demand for the computational power of the network needed to process smart contracts and other transactions.
A standard ETH transfer requires a gas limit of 21,000 units of gas. The more complex the commands you want to execute, the more gas you have to pay.
The amount of fees being spent on the Ethereum network is higher than ever before (now even higher than the single day in June with anomalous fees unrelated to regular network usage). This spike in fees has been caused by a high demand for space on-chain, with the median gas price reaching an all-time high of 217 Gwei.
The total cost of an Ethereum transaction is actually the amount of necessary gas multiplied by the price in GWei per gas unit. This is the maximum transaction fee we'll pay; any extra gas is refunded, so fees are often vastly overestimated.
1 Gwei equals 0.000000001 or 10-9 ETH. Conversely, 1 ETH equals one billion (109) Gwei.
