All terms
The fee you pay to have the network process your transaction.
Gas is the unit measuring computational work on Ethereum and similar chains. A simple transfer costs 21000 gas. A complex swap might cost 200000. You pay gas units multiplied by a gas price, denominated in the network's native token.
Gas exists to stop spam. If computation were free, anyone could paralyze the network with junk. Attaching a real cost makes attacks expensive and prioritizes transactions people actually care about.
On Ethereum a swap might cost several dollars. The same swap on Base or Solana costs a fraction of a cent, which is the entire reason layer 2 networks exist.
That gas is a fee the network charges for profit. It is a price for scarce block space, set by an auction between everyone trying to transact right now. Nobody sets it, which is why it swings so wildly, and why waiting an hour can genuinely halve it.
Common questions
Why is gas so expensive sometimes?
Do I pay gas if my transaction fails?
Where to go next
More foundations terms
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