A currency pair is an exchange relationship of one currency in terms of another. When you trade forex, you buy or sell a currency pair. As you begin trading forex, your main focus should be on major pairs and highest paying crosses. The most traded pairs include: EUR/USD, USD/JPY, GBP/USD, USD/CHF, AUD/USD and USD/CAD. The first listed currency in a currency pair is called the base currency, and the second currency in a pair is called the quote currency. All the major currencies have highly liquid markets that trade 24 hours a day and attract very low spreads.