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Currency is a natural occurance aimed to solve these things with bartering:
1) Currency doesn't lose value rapidly as time goes on, compared to some other things like foodstuffs
2) Currency is "continuous", that is, you can "split it" almost infinitely so you can get exactly as much in a trade as you want
Quite a lot of things can work as a substitute, for example, salt was used by some cultures as currency, but it is unoptimal.