Driving a car = need to pay for gasoline. Using Ethereum = need to pay for gas. Whenever you make an in-app purchase on your iPhone, Apple takes a 30% cut because they host the app on their app-store. This is similar, except Ethereum isn't run by a company,** fees help secure the network**. ### **Why are gas fees always changing in price?** At the moment, gas fees can be unpredictable because they are controlled by **demand & network usage**. So if a lot of people start driving cars everyday, gasoline prices will go up, same with ETH gas fees. (This will be fixed soon so that gas fees are predictable and stable) ### **Why are gas fees called "gwei"?** A: For the same reason we don't say "zero point zero one dollar ($0.01), but instead say, "one penny" or "one cent". Gwei makes very small fractions of the ETH currency easier to visualize. To clarify: **1 Gwei = 0.000000001 ETH (10-9)**. This is why you may see the current gas price being quoted at, say, 200 gwei. https://ethgasstation.info/