Wei

The smallest division of the Ethereum network's native cryptocurrency Ether (ETH), used especially to calculate transaction payments on the network.

When referring to smaller amounts of ETH, Wei is used especially in transactions that accrue the lowest fees. 1 Ether is equivalent to 1e18 wei or 1 x 10¹⁸ wei.

Wei and its multiples such as Kwei and Gwei provide a convenient way to describe small value transactions that cost fractions of ether.