$ETH A coin pair like ETH refers to trading Ethereum (ETH) against another currency on a cryptocurrency exchange. In a pair ETH is either the base or quote currency, depending on the trade direction. For example, in the ETH/USD pair, ETH is traded against U.S. dollars. Traders buy or sell Ethereum based on price movements between the two currencies. Coin pairs make it easier to assess the value of one cryptocurrency relative to another asset. $ETH pairs are extremely popular due to Ethereum's strong market position, liquidity, and role in decentralized finance (DeFi) and smart contract platforms.