What is a gas fee?

Gas is the unit of computational work a transaction consumes. The fee is that amount multiplied by a price users bid, so it rises with demand for block space.

Why it matters

Fees are set by an auction, not a schedule, so the same action can cost wildly different amounts an hour apart. A failed transaction still consumes gas — you pay for the attempt, not the outcome, which surprises people the first time an approval reverts. Fees are also paid in the network’s own asset, so you must hold some of that asset to move anything else, and running out is a common way to become temporarily stuck.