Australia is a country in Oceania bordering the Indian Ocean and the Southern Pacific Ocean. Australia comprises mainland Australia, the island of Tasmania, and several small islands in the Indian and Pacific Oceans. The terrain is mostly low plateau with deserts. The government system is a federal parliamentary democracy and a commonwealth realm. The chief of state is the Queen of the United Kingdom, and the head of government is the prime minister. Australia has a mixed economic system which includes a variety of private freedom, combined with centralized economic planning and government regulation. Australia is a member of the Asia-Pacific Economic Cooperation (APEC).