Petroleum is discovered in Titusville, Pennsylvania, leading to the world's first commercially successful oil well.

Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term petroleum refers both to naturally occurring unprocessed crude oil, as well as to petroleum products that consist of refined crude oil.

Titusville is a city in the far eastern corner of Crawford County, Pennsylvania, United States. The population was 5,262 at the 2020 census. Titusville is known as the birthplace of the American oil industry and for a number of years was the leading oil-producing region in the world. It was also notable for its lumber industry, including 17 sawmills, as well as its plastic and toolmaking industries. It is part of the Meadville micropolitan area.

An oil well is a drillhole boring in Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produce only gas may be termed a gas well. Wells are created by drilling down into an oil or gas reserve and if necessary equipped with extraction devices such as pumpjacks. Creating the wells can be an expensive process, costing at least hundreds of thousands of dollars, and costing much more when in difficult-to-access locations, e.g., offshore. The process of modern drilling for wells first started in the 19th century but was made more efficient with advances to oil drilling rigs and technology during the 20th century.