Mercosur or Mercosul (Spanish: Mercado Común del Sur, Portuguese: Mercado Comum do Sul, Guarani: Ñemby Ñemuha, English: Southern Common Market) is an economic and political agreement among Argentina, Brazil, Paraguay, Uruguay, and Venezuela; with Bolivia becoming an accessing member on 7 December 2012 to be ratified by the Member State's legislatures.

Its purpose is to promote free trade and the fluid movement of goods, people, and currency. The official languages are Guaraní, Portuguese and Spanish. It has been updated, amended, and changed many times since. It is now a full customs union. Mercosur and the Andean Community of Nations are customs unions that are components of a continuing process of South American integration connected to the Union of South American Nations.