Free trade area is a designated group of countries that have agree to eliminate tariffa, quotas and preferences on most goods between them.
It can be considered the second stage of economic integration.
Countries choose this kind of economic integration form it their economical structures are complementary. If they are competitive, they will choose customs union.
Unlike a customs union, members of a free trade area do not have the same policies with respect to non-members, meaning different quotas and customs.