There are some currencies that are far more popular trades than others, they are called the major forex currency pairs, and they are as follows:

The majors:  GBP/USD, EUR/USD, USD/CHF, USD/JPY

The commodity pairs:  AUD/USD, USD/CAD, NZD/USD

The Majors:

• GBP/USD – The GBP/USD (Pound Sterling/US Dollar) is nicknamed ‘Cable’ due to the undersea cables that used to carry bid and ask quotes across the Atlantic Ocean. This major forex pair shares similarities with the EUR/USD. Both are highly correlated because the United Kingdom’s economy is tied to the European Union. Traders enjoy tight bid-ask spreads on the GBP/USD due to its high liquidity.
• EUR/USD – The EUR/USD (Euro/US Dollar) nicknamed ‘Fiber’ is the world’s most traded currency pair commanding 23% of FX transactions in 2016. The Euro and the US Dollar represent the two largest economies in the world, the US Economy and the European Union. The popularity of the EUR/USD ensures that it trades at tight spreads. High volumes lead to reduced price differences between the bid and offer.
• USD/CHF – The USD/CHF (US Dollar/Swiss Franc), nicknamed ‘Swissy’, derives its popularity from the Swiss Franc’s safe-haven status. When risk/volatility enters the market, traders bid up the Swiss Franc because the Swiss economy is seen to have lower risk.
• USD/JPY – The USD/JPY (US Dollar/Japanese Yen) is also known as ‘The Ninja’ and is the second most traded currency pair. The Bank of Japan has had to combat low inflation and growth for many years, and as a result it has a very low interest rate. The USD/JPY is also traded in extremely high volumes which lead to low bid-ask spreads and lots of liquidity. The Yen is also known as a safe-haven currency amongst traders.

The commodity pairs:

• AUD/USD – The AUD/USD (Australian Dollar/US Dollar), or ‘Aussie’, is greatly affected by mining commodities, farming of beef, wool and wheat. The Aussie also tends to do well when China does well because the two countries are big trading partners. The Reserve Bank of Australia (RBA) also has major influence over the AUD/USD.
• USD/CAD – The USD/CAD (US Dollar/Canadian Dollar) or ‘Loonie’ is also heavily affected by oil, timber and natural gas. Interestingly, the Canadian dollar is closely tied to the US economy.
• NZD/USD – The NZD/USD (New Zealand Dollar/US Dollar), also known as the ‘Kiwi’, is heavily influenced by data releases of agriculture and tourism. As with all currencies, these central banks (Federal Reserve and Reserve Bank of New Zealand) shouldn’t be underestimated. Changes to monetary policy from either of them can lead to NZD/USD volatility.

Notice that all of these pairs are tied to the U.S. dollar. This doesn’t give a trader many options when most of their trading decisions are based on this one speculation. Major currency pairs all contain the US Dollar on one side – either on the base side or quote side. They are the most frequently traded pairs in the forex market. The majors generally have the lowest spreads and are the most liquid. The EUR/USD is the most traded pair with a daily trade volume of nearly 30% of the entire forex market. These are the most liquid currencies, I.e. they are the most actively traded currencies in the world. They constitute about 85% of the total trading volume in the forex market.