Australia, officially the Commonwealth of Australia, is a vast island continent and country located in the southwestern Pacific Ocean. It is the sixth-largest country by area and the largest country in Oceania. The nation is characterized by immense geographical diversity, ranging from arid interior deserts and tropical rainforests to temperate coastal regions. Its population of over 25 million people is spread across a continent that is also the world's oldest, flattest, and driest inhabited landmass. The country's unique biodiversity and rich natural resources underpin its economy and culture.