In the cryptocurrency world, the so-called "trading pair" refers to a combination of using one currency to buy another. For example, BTC/USDT commonly seen on Binance means you can use USDT (a stablecoin) to buy BTC (Bitcoin), or exchange BTC for USDT. The most commonly used currency by the general public is USDT as a base currency because it is more stable and not prone to large fluctuations. Some people also use BNB or ETH to exchange for other coins, depending on which has lower transaction fees or which coin is currently popular. Choosing the right trading pair can sometimes affect your costs and trading efficiency.