The United States courts of appeals or circuit courts are the intermediate appellate courts of the United States federal judiciary. The courts are divided into 13 circuits, and each hears appeals from the district courts within its borders, or in some instances from other designated federal courts and administrative agencies. Appeals from the circuit courts are taken to the Supreme Court of the United States. The district, appellate, and Supreme courts are all authorized under Article Three of the United States Constitution, giving them the exclusive functions as constitutional courts.