Canada uses a federal form of democratic government that brings together a number of different political communities under a common government for mutual purposes, and separate regional governments for the particular needs of each region. This form of government takes into account Canada's geographical realities, the diversity of its cultural communities and its dual legal and linguistic heritage. Canada has three levels of government: federal, provincial and territorial, and municipal (local or regional). Within the federal structure, elected officials Ð the Cabinet of ministers under the leadership of the Prime Minister Ð make up the chief decision-making body. The federal government leads the country's democratic system of governance through consultations with other elected officials, provincial and municipal representatives, and the Canadian public. The principal role of the Canadian government is to ensure and support the country's economic performance. Its other responsibilities include national defence, interprovincial and international trade and commerce, immigration, banking and the monetary system, criminal law and fisheries. The federal government also oversees such industries as aeronautics, shipping, railways, telecommunications and atomic energy.