Money.
Duh.
Trading in the forex market, it will always involve two currencies at a time.
These are called ‘currency pairs’,
But while you can trade almost any currency pair in theory, there are certain pairs that are consistently the most traded. These are referred to as ‘major pairs’ or ‘majors’. These major pairs make up 80% of the entire trading volume in the forex market
Currency pairs are made up of the base currency and the quote currency. The difference in price is where you’ll make your profit or loss.
The currency that is listed first is called the base currency, and the currency listed second is called the quote (or counter) currency.