Recently, there has been serious turmoil in the Venezuelan and Turkish currency. In fact, all currencies are always in crisis. The only possible exception would be the Swiss franc as there are more gold reserves to support it than any other country has for its own currency.
When they say that the dollar is strong, what they really mean is that the dollar is losing less value at a slower pace than the other floating value currencies.
History indicates that all paper currencies that have ever circulated have failed. Some lose value slowly while some lose value quickly. You need to be extremely careful when your currency is losing value fast like it is now in Venezuela and Turkey. The same thing happened in the past several decades in Russia, Mexico and a few countries in South America and Africa. These situations are very dangerous. You also need to be aware that fast declines in another country can have an impact on our own currency.
in the case of the American dollar, it has been in a slow decline for a long time.
The initial trend down started in 1933-1934 when President Roosevelt made it illegal to own gold and changed the exchange rate of gold and the dollar. The primary reason was to allow the Federal Reserve to print money without constraints. This was the first large scale official action to devalue the dollar.
The final blow to the dollar was in 1971 when President Nixon stopped the conversion of dollars to gold for foreign exchange, thereby eliminating the gold standard for the dollar. This was supposed to be temporary but it has never been reversed and the dollar has lost much of its value and has been reduced to a small fraction of its previous worth. It is constantly being devalued by money printing and inflation.
Note:If interested, Paul Krugman, Nobel prize winner in Economics in 2008, wrote an analysis in 1996 of the aftermath of all this and the present concerns for the new floating rate system of currencies.
For you, the financial implications are very important. You always need cash for daily use and some extra for future events and emergencies. After those cash requirements have been placed in savings, your remaining cash should not be considered an investment. It is a temporary holding while you wait for suitable investments.
Read INVESTMENT DILEMMA for further information.