Oil is a thick, black liquid that comes from deep within the Earth. It is formed from the remains of ancient plants and animals that have been buried and transformed over millions of years. People extract oil to use as fuel for cars, airplanes, and heating, as well as to make products like plastic and cosmetics. Oil is an important part of the global economy, influencing everything from gasoline prices to international relations. Countries rich in oil, like Saudi Arabia and Venezuela, often have significant power in the world. However, using oil also raises concerns about pollution and climate change.