Robert Kyosaki is one of my favorite writers for the Yahoo! Finance webpage. He is really able to take a difficult concept and explain it so that even the unlearned person can understand it. Here he talks about the fact that we have an over supply of US dollars in the world today and our purchasing power is decreasing because many nations do not want any more of them.
He suggests that a prudent investor would go and buy silver and / or gold in order to have what he terms as international currency that can be traded for nearly anything at anytime because the demand for those items will remain high no matter what the dollar does.
I agree that this would be wise since the value of the dollar has fallen and the value of silver and gold has really escalated in the recent past and if the reverse ever happens, gold and silver are easily traded back to dollars with relatively no problem at all.