Although the WTO embodies the principle of non-discrimination in international trade, Article 24 of the GATT authorizes the creation of free trade zones and « customs unions » among WTO members. A free trade area is a group of countries that remove all tariffs on trade with each other, but retain their autonomy in setting their tariffs with non-members. A customs union is a group of countries that remove all tariffs on trade between them, while maintaining a common external tariff for trade with countries outside the EU (which is technically contrary to the MFN). In most modern economies, there are many possible coalitions of interested groups and the diversity of possible unilateral barriers is important. In addition, some trade barriers are created for other non-economic reasons, such as national security or the desire to protect or isolate local culture from foreign influences. It is therefore not surprising that successful trade agreements are very complicated. Some commonalities of trade agreements are (1) reciprocity, (2) a clause of the most favoured nation (MFN) and (3) the use of non-tariff barriers. For most countries, international trade is governed by unilateral trade barriers of various kinds, including tariffs, non-tariff barriers and absolute prohibitions. Trade agreements are a way to reduce these barriers and thus open up the benefits of enhanced trade to all parties. In the modern world, free trade policy is often implemented by a formal and reciprocal agreement between the nations concerned. However, a free trade policy may simply be the absence of trade restrictions. A trade agreement signed between more than two parties (usually neighbouring or in the same region) is considered multilateral. They face the main obstacles – to content negotiation and implementation.
The more countries involved, the more difficult it is to achieve mutual satisfaction. Once this type of trade agreement is governed, it will become a very powerful agreement. The larger the GDP of the signatories, the greater the impact on other global trade relations. The largest multilateral trade agreement is the North American Free Trade Agreement between the United States, Canada and Mexico.  There are a large number of trade agreements; some are quite complex (the European Union), while others are less intense (North American free trade agreement).  The resulting level of economic integration depends on the specific type of trade pacts and policies adopted by the trade bloc: the United States has signed bilateral trade agreements with 20 countries, including Israel, Jordan, Australia, Chile, Singapore, Bahrain, Morocco, Oman, Peru, Panama and Colombia. The best possible outcome of trade negotiations is a multilateral agreement that encompasses all major trading countries.