Currencies are traded in pairs as their value is relative to one another. The first currency shown is the controlling one in terms of placing your order. So if you see EUR/USD then you are al-ways choosing to buy or sell the first currency (Euro) against the second currency (U.S. Dollar).
MAJORS are widely traded by beginners and profes-sionals alike. This is because they have the most liquid-ity, lowest spreads and the broadest range of move-ments. Unlike small currencies, majors are generally more stable. The economic and political institutions of these nations are generally long established and pre-dictable compared to other nations.
THE CROSSES are any currency pair that doesn’t fea-ture the USD and they do not hold any less profit po-tential than the majors. Too much US Dollar exposure can lead to all your trades heading in the same direc-tion, a big problem if that direction is against you.
THE "EXOTIC" currency pairs are less traded and so much more costly to buy or sell. Don’t let the cost put you off, because many of the greatest traders of all time made their fortunes with exotics. For example, one of the 5 greatest forex traders, George Soros gained $800 million profit from selling Thai Baht (THB) in 1997 Asian crisis.