Before the introduction of the euro, the official currency of Estonia was the Estonian kroon (EEK). Estonia began using the Estonian kroon after gaining independence from the Soviet Union in 1991. During the process of European integration, Estonia joined the European Union in May 2004, a significant step that paved the way for the adoption of the euro as the official currency. The Bank of Estonia is the institution responsible for managing monetary policy and overseeing the country's financial system, providing an important reference point for understanding the history and evolution of Estonian coins.