One very common suggestion is to buy gold and silver in case of a collapse. The concept is that these will have value and despite whatever goes on with your money in the bank or your currency, you will at least retain some value of your wealth or past labor. Will gold or silver really make a difference?
There are actually two forms of collapse when this word is used. One is a economic collapse and the other is a total collapse of society as we know it.
In an economic collapse, this means that your economy and your currency are having problems and lose value. In this situation your gold and silver could be exchanged for other currencies so that you can keep the value of that money you earned. If it was kept in your current currency and not gold and silver, you will lose that value in an economic collapse.
In a total collapse of society as we know it, gold and silver probably won’t be worth much for quite awhile. Real goods like food, water, electricity, defense, shelter, and others will have a much higher value. If there is a limitation on food, hungry people are not going to trade food for gold. If you do end up getting lucky enough to make this trade, you will do so at a very high price. When society comes back together, eventually that gold and silver would have some value. In the mean time, actual goods will be easier to use and trade than precious metals.