Gwei
Also known as: gigawei
A small denomination of Ether (one-billionth of an ETH) commonly used to price Ethereum gas fees.
Definition
Gwei is a unit of Ether equal to 0.000000001 ETH (10⁻⁹). Gas prices on Ethereum are usually quoted in gwei because full-ETH amounts would be unwieldy. While gwei itself is just a unit, it matters for tax indirectly: gas costs quoted in gwei must be converted to ETH and then to rands to record fees accurately in your base cost or proceeds.
Example
A transaction costs 30 gwei per unit of gas; you convert the total gas spent into ETH, then into rands, to record the fee correctly.