All currency abbreviations in the foreign exchange market are composed of three English letters, the first two letters represent the country or region, and the third letter represents the currency of the country or region. 
In the case of NZD, NZ stands for New Zealand and D stands for New Zealand dollar. 
The currencies included in the chart, we became the “major” currency, because they are the most widely used internationally.
Currency pair 
Foreign exchange trading refers to the trading method of buying one currency and selling another currency at the same time. Currencies are traded in pairs by brokers or dealers, such as euro / dollar (EUR / USD) or pound / yen (GBP / JPY). 
When you trade in the foreign exchange market, you are buying and selling currency pairs.
We can think of each currency pair as a “tug of war” between different currencies. The fluctuation of the exchange rate depends on the strength of the currency at a certain moment. 
Major currency pairs
The currency pairs listed in the table below are called “major currency pairs” or “straight markets”. These currency pairs all contain US dollars, and the frequency of transactions is also the largest. These currency pairs are the most liquid and the most widely traded currency pair in the world.
What are the main currencies in the foreign exchange market-Yuhui International.  
Major cross currency pairs 
We refer to currency pairs that do not contain the US dollar as “cross currency pairs,” or “cross-overs.” The most active cross currency pairs include the three major currencies except the US dollar: the euro, the yen, and the pound.
Currency pairs of other countries 
The currency pairs of other countries are composed of a major currency country and other emerging economies, such as Brazil, Mexico or Hungary. 
Through your foreign exchange broker, you may see the following exotic currency pairs. Keep in mind that the trading volume of these currency pairs is not as large as the main currency pairs or cross currency pairs, so their transaction costs are usually higher. 
It is not surprising that the spreads of foreign currency pairs we have seen are two to three times the euro / dollar or dollar / yen. Therefore, if you plan to trade foreign currency pairs, please keep this in mind.