Gas
The unit Ethereum uses to measure the work a transaction needs. The fee is the gas used multiplied by the price per unit.
Gas in more detail
Ethereum measures the work a transaction needs in units of gas. A simple transfer of ETH uses 21,000 gas. Moving a token or using a smart contract uses more.
You pay in the network's own coin. Sending a token on Ethereum needs ETH for gas. Keep a little in the wallet.
Failed transactions still cost. If a transaction runs out of gas or the contract rejects it, the work was still done and the fee is still charged.
All 128 terms · Checked against the lesson's sources on 8 October 2026.
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