Tax, tariff and tradeThe tax, tariff and trade laws of a political region, state or trade bloc determine which forms of consumption and production tend to be encouraged or discouraged. All three are often changed by a trade pact.
Tax policy, to encourage or discourage particular types of consumption or production in the jurisdiction.
Tariffs, or lack thereof, to encourage or discourage imports or consumption inside the jurisdiction.
Trade, especially investment, policy to encourage or discourage location of particular types of activity in the jurisdiction, especially leading to export opportunities.
The EU, has a particularly strong form of integration of the three, fixing the targets of taxation, ending most internal tariffs, and building a common West European trade bloc. Recently they also developed a common currency, the Euro. Monetary integration is considered a separate issue, and indeed the Euro was not implemented until long after acceptance of tax, tariff, trade rules.