$BTC A coin pair, such as BTC/USD, is a trading pair on cryptocurrency exchanges, where BTC (Bitcoin) is traded against another currency, in this case, the U.S. dollar (USD). Coin pairs allow traders to exchange one cryptocurrency for another or for fiat money, depending on the pair. BTC is the base currency in this pair, while USD is the quote currency. The price of BTC/USD indicates how much one Bitcoin is worth in U.S. dollars. Traders use this pair to speculate on Bitcoin's price movements, hedge against price volatility, or accumulate more BTC. It is one of the most popular and liquid trading pairs across major cryptocurrency exchanges worldwide.