Since WTO members are required to communicate their free trade agreements to the secretariat, this database is based on the official source of information on free trade agreements (called the WTO-language regional trade agreement). The database allows users to obtain information on trade agreements that are communicated to the WTO by country or theme (goods, services or goods and services). This database provides users with an up-to-date list of all existing agreements, but those that are not notified to the WTO may be lacking. In addition, reports, tables and graphs containing statistics on these agreements, including preferential tariff analysis, are presented.  First, tariffs and other rules applicable to trade with non-parties to this free trade area in each of the parties that signed a free trade area in force at the time of the creation of this free trade area must not be higher or more restrictive than tariffs and other rules applicable in the same signatory countries prior to the creation of the free trade area. In other words, the creation of a free trade area to give preferential treatment to their members is legitimate under WTO law, but parties to a free trade area are not allowed to treat non-parties less favourably than before the creation of the territory. A second requirement under Article XXIV is that tariffs and other trade barriers must be eliminated primarily for all trade within the free trade area.  There are significant differences between unions and free trade zones. Both types of trading blocs have internal agreements that the parties enter into to liberalize and facilitate trade between them. The key difference between unions and free trade zones is their approach to third parties [lack of ambiguity needed].
While a customs union requires all parties to apply and maintain identical external tariffs on trade with non-parties, parties to a free trade area are not subject to such a requirement. Instead, they can set and maintain any customs regime for imports from non-parties, as they see as necessary.  In a free trade area without harmonized external tariffs, the parties will adopt a system of preferential rules of origin to eliminate the risk of trade diversion [necessary ambiguities].  It should be noted that with regard to the qualification of the original criteria, there is a difference in treatment between inputs originating and outside a free trade agreement.