In the oil and gas industry, what does the abbreviation API stand for?

In the oil and gas industry, API stands for the American Petroleum Institute.

The American Petroleum Institute is a major trade association representing the United States petroleum and natural gas industry. Founded in 1919, it develops technical standards, publishes industry data, and advocates on energy policy.

API is also familiar from petroleum measurements. The API gravity scale, developed by the institute, indicates whether a petroleum liquid is lighter or heavier than water. API standards additionally cover equipment, safety practices, environmental performance, and testing methods used around the world.

A common mix-up is confusing the institute with an individual measurement: API can refer to the organization, while “API gravity” refers to a petroleum-density scale. The institute is headquartered in Washington, D.C., and its standards are widely used beyond the United States.