Depreciation/appreciation refers to the change in price of a currency primarily as a
result of changes in demand and supply under a floating exchange rate environment.
For example, when foreign countries buy canadian dollars to purchase canadian
resources, the increase in demand for canadian dollars increases the value of the
dollar (i.e., currency appreciation). Examples of depreciation and appreciation of the
canadian dollar can be seen every day in the market place when you hear about
changes in the value of the loonie.
Devaluation/revaluation refers to a change in the relative value of a currency as a
result of deliberate government decision to change the value of the currency under a
fixed exchange rate regime. Examples of devaluation are not as common as
depreciation. For more, you can enter devaluation in an internet search engine to
view more information.