A confederacy is a union of independent states or groups that come together for a common purpose, often to achieve mutual benefits while maintaining their sovereignty. This arrangement allows member states to collaborate on issues like defense, trade, or governance without losing their individual authority. Historically, confederacies have been formed for various reasons, such as the Articles of Confederation in the early United States, which aimed to unify the thirteen states during and after the American Revolutionary War. Another example is the Swiss Confederation, which began as a defensive alliance among several cantons in Switzerland.