Why does money depreciate?

Depreciation of money is brought about by a decline in the price of a particular currency in terms of other currencies, thereby lowering the foreign exchange value of the first currency.

Currency depreciation is the loss of value of a country's currency with respect to one or more foreign reference currencies, typically in a floating exchange rate system. It is most often used for the unofficial increase of the exchange rate due to market forces, though sometimes it appears interchangeably with devaluation.

Think of it this way, it's simpler;
Each dollar, pound, yen or whatever is really only a voucher and it's value doesn't change. As prices increase these vouchers will get you less goods so it only APPEARS to be worth less. We always say that money is depeciating but it is more accurate to say costs are appreciating (rising)

Because of inflation.
When the cost of living goes up, each dollar can buy less and is hence worth less.
This decreases its value.

money appreciates faster when is seen as a seed of investment also as oxygen for life so as money for investment