Chevron Corporation is a United States multinational energy company. A successor of Standard Oil, it is based out of San Ramon, California, and is involved in every aspect of the natural gas, geothermal energy and oil industries. Operating in more than 180 countries and employing around 62,000 people, Chevron is one of the world's biggest oil companies. It ranked third in a Fortune 500 list of public corporations and sixteenth on their list of the top 500 corporations in the world. One of the first fuel brands to be Top Tier certified, they sell an average of 3.1 million barrels of diesel, jet fuel and gasoline per day.