What do we mean when we talk about the official foreign currencies exchange rate? In all the countries in the world there is an official exchange rate according to the reference currency, the dollar, and also with the currencies of other countries.
The official foreign currencies exchange rate can be seen for example, when you fix an exchange rate for currencies. For example, the dollar exchange rate is the exchange rate of a currency according to dollars.
The official foreign currencies exchange rate stays in the same value beacuse of the authorities,in this case the Central Bank of each nation. This is the entity in charge of keeping the official foreign currencies exchange rate in the established levels, and so the monetary entity avoids the devaluation of the currency or the appreciation over the values established by the ones of the political economy.
Knowing the official foreign currencies exchange rate is something I should do if I choose to invest on foreign currencies. The difference that there is between the exchange rates of each country can help its economy. A dollar, for example, will not quote the same in Argentina or in Europe, as the argentine exchange rate is very devalued in front of american currency and euro is over the dollar value.
The official foreign currency exchange rate is one of the principal bases of the political economy of a country. On this decision depends which sector is being considered by an economic model, if a government decides to help exports it will probably devalue its currency according to the dollar to give an incentive to this sector. And if the model is trying to do the opposite it will probably appreciate local currency regarding to the dollar. This measure will help imports and stop national industry.

The currencies of different countries of the world have a particular characteristic: Not all have the same force, or the same support. That’s why when we talk about foreign currencies exchange, there are currencies that have minor value in front of others and at the monetary market they are called weak currency.
When you want to exchange foreign currencies we should consider which and what is the exchange rate. An exchange rate is the difference of value between two currencies , that means that it is the currency needed to buy the other.
foreign currencies exchange can be done with currencies in which the value dollar does not intervene, for example yen/Swiss franc at 156.60, this exchange rate that is called crossed means that a yen can be changed per 156.60 Swiss franc.
When we talk about foreign currencies exchange, we should also consider that there are two different kinds of exchange rates. One is the flexible system and the other is the fixed one.
In the flexible exchange rate system the Central Bank, adjust the exchange rate to modify the supply and demand to generate a major or minor income of foreign currencies.
A fixed exchange rate system will be very favorable for whom want to exchange foreign currencies as currencies do not fluctuate, they are fixed one according to the other. This kind of exchange rate makes the monetary authority Central Bank have an important reserve of national currency as foreign currency. In Argentine, for example, during the 90’s they set up an exchange rate fix, fixing the peso to the dollar, and so, this allowed foreign currencies exchange to be favorable to get consumer goods and travel abroad.