Foreign exchange (FOREX)
The buying and selling of currency

=> Consumer Taste
=> Relative income
=> Relative Price Level
=> Speculation

Appreciation of the dollar causes American goods to be relatively more expensive and foreign goods to be relatively cheaper thus reducing exports and increasing imports

Depreciation of the dollar causes American goods to be relatively cheaper and foreign goods to be relatively more expensive thus increasing exports and reducing exports

Specialization
Individuals and countries can be made better off it they will produce in what they have a comparative advantage and then trade with others for whatever else they want/need

Absolute and Comparative Advantage
Absolute Advantage
The producer that can produce the most output or requires the least amount of inputs (resources)

Comparative Advantage
The producer with least opportunity cost

Countries should trade if they have a relatively lower opportunity cost. They should specialize with the good that is "cheaper" for them to produce

Distinguishing input from output problems the output problems presents the data as products produced given a set of resources
An input problem present the data as amount resources needed to produce a fixed amount of output (example number of labor unions to produce 1 bushel)