When you combine all major currencies, those that contain USD are considered as a major, the others that don't contain this currency are considered as minors.
- Major Currency is the EUR, USD, JPY, CHF, GBP, CAD, NZD.
- Exotic Pairs are any cross pairs that don't contain two major currencies.
- The major pairs have lots of volumes. Therefore, tend to attract most traders, which keeps the volume high and spread low.