Canada is a parliamentary democracy and a constitutional monarchy in the Westminster tradition. The country's head of government is the prime minister—who holds office by virtue of their ability to command the confidence of the elected House of Commons—and is appointed by the governor general, representing the monarch, who serves as head of state. The country is a Commonwealth realm and is officially bilingual at the federal level. It ranks among the highest in international measurements of government transparency, civil liberties, quality of life, economic freedom, and education. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many other countries. Canada's long and complex relationship with the United States has had a significant impact on its economy and culture.