The US dollar index is used to measure the value of the dollar against a basket of six foreign currencies.
These are: Euro, Swiss Franc, Japanese Yen, Canadian Dollar, British Pound and Swedish Krona.
The index was established shortly after the dissolution of the Bretton Woods Agreement in 1973 with a base of 100, and values have been at that base ever since.
The value of the index is a fair indicator of the value of the dollar on world markets.