Super Random Thought:
Money in itself is inherently worthless. The value in money lies in what it represents - and in contemporary society, currency is backed by the value of its issuing country's economy. Money was invented because it's more effective than bartering. A shoemaker can't barter with other people who aren't in need of shoes, and a farmer can't barter when his crops aren't ready for harvest etc. Initially things of inherent worth were used as currency (e.g. precious things), but this became problematic when people started making huge purchases. Paying for land is impractical if you have to transport wagon-loads of silver or gold etc., then there's the problem of security. The Chinese were the first to invent paper money - the idea of a central authority securing precious assets and then essentially printing out notes that people could use at a later point in time to redeem those assets. But then people figured out that the assets never needed to be redeemed as people could literally trade in these government-issued "I owe you" notes. This idea transmitted along the Silk Road to Italy who then adopted it and it spread through Europe. The Europeans introduced the idea of banking, allowing assets to be deposited or withdrawn from branches rather than just a central location. But this still had problems in terms of the physical distance between branches and also trading between different banks. Today we can lose money when we exchange currencies from different countries, but back then people could lose money from exchanging currencies between different banks at the next town!

And if a bank collapsed then that bank's currency would become utterly worthless. I think it was either the English and/or the Dutch (

not sure

) who introduced the idea of centralised government banking. Governments are far more secure and far less likely to collapse than banks, especially currencies from stronger economies - which is why these countries' currencies are worth more than those from weaker economies. Hypothetically speaking, if the Australian economy collapsed tomorrow, the AUD would become worthless. But precious things like gold and silver etc. would still be worth something because they have inherent value. Money doesn't. It's the purchasing power of money that makes it valuable.