exchange rates---The
interconnecting valuation mechanism between different areas/countries. Valuation can also be reflected in price
quotes of a particular good in a reserve currency.
Some exchange rates are highly speculated on, and some are purposely fixed, or
pegged to another rate and do not float freely, and could result in multi-year
trade imbalances between nations where one nation becomes indebted to another. There
are infinite exchange rates in a global economy other than just between
currencies, in my mind anyway, having to do with individual preferences and ordinal prices.
See also gold standard,
opportunity cost
and utility curves below.