A bit of history is needed to explain the following post.
Most countries use 2 kinds of 'valuables' what we call 'money'.
(stamps can be considered as a third kind of 'valuables' - since they also represent money - but here i talk about what we generally consider as 'money)
There was a time when 'swapping' was all we needed to trade with other people.
If you didn't have anything to swap at them moment of trade, you were excluded of trade.
'Money' offered a solution for that problem. Money itself has no value, you can't eat it, cant drink it, can't build a house with it, and one has to admit, it's barely big enough to make it into a wearable suit of dress...
But 'money' represented not the goods itself, it represented the 'value' of the goods. Since with the money you got from a trade, you could buy later one, goods for a similar value.
In the old days, people weren't always sure that the money they received after an exchange, would still be accepted elsewhere or would keep it's value (... thinking of that sentence, I must admit nothing has changed much :-) )
Therefor, 'money' was made in valuable metals, such as gold, silver...
Gold and silver were exchangable worldwide, and had a certain stability.
I'm skipping a big part of history now, to come to the topic of today.
During and after the first world war, european people were aware that lots of coins in circulation were still made "minted" in valuable materials, mainly silver.
To assure themselves some savings for the post-war era, those silver coins were kept in a safe place.
No matter who would rule the country after the war, and coins that could loose trade value, silver would always be silver. This resulted in a shortage of those metals for the production of coins, and due to a shortage of circulation coins, some gouvernements started to 'print' their coins.
Coins are normally 'minted' for example by the "Royal Mint" and banknotes are 'printed' for example by the "National Bank".
Due to a shortage of silver, in this case, the Dutch Royal mint, started to issue notes, representing the coins.
In a way one can speak of a paper version of a coin.
This all happened in many European countries, after the first and second world war.
The 'notes' are in fact coins.
To make that clear, the first 'note' I show here (sorry for the bad quality) shows the word 'ZILVERBON'.
This, to make clear that the note in fact was representing the formerly known 1 Guilder (silver) coin.
Let's take a closer look to the front side :
The word : zilverbon (silver bon) can be read on top
Wettig betaalmiddel = legal tender
and despites of the black fold, there's something else that can be found on the note.
The world 'EEN GULDEN' (one guilder) is printed in large letters, of which only the outlines can be seen.
For those who can't find it :