Gwei (gwei) is a small denomination of the cryptocurrency Ethereum (ETH). It is the most common unit that is used to calculate micro-transactions within the Ethereum network, taken from the popular Wei denomination, which is one-billionth of one ETH (1 ETH = 1,000,000,000 Wei). Gwei is the equivalent of 0.000000001 ETH, and 0.000001 of an Ether, represented as 1 gwei = 0.000000001 Ether = 0.000001 Ether.

Gwei is also used for Ethereum gas prices, as it is much easier to use, compared to Wei. Ethereum gas is the pricing model used to determine the cost of executing smart contracts or transactions on the Ethereum network. It is like a fee or payment to the miners confirming, verifying and processing a transaction. The higher the gas price, the faster a transaction is confirmed, as the miners prioritize getting paid higher fees. The price of Gwei will eventually reflect the market rate for buying and selling ETH.

Gwei is a unit of one-billionth, and makes it much easier to specify Ethereum gas prices. Because of this, many cryptocurrencies have adopted this naming convention for their micro-denominations in order to facilitate easy transaction fees. Popular services, such as cryptocurrency exchanges, wallets, and digital treats like CryptoKitties (the blockchain game using ETH) typically quote prices in Gwei.

Overall, Gwei is a micro-denomination of Ethereum, and serves as the currency to buy and sell goods and services within the Ethereum network. The use of Gwei makes it easier to specify Ethereum gas prices, allowing miners to be paid the market value for their transactions. The popular Wei denomination is likely to be extended and adopted by other cryptocurrencies, solidifying its place as the industry standard for small denomination transactions.