An oil-processing plant, also known as a refinery, is a facility that takes crude oil and processes it into more useful products such as gasoline, diesel fuel, and various types of petrochemicals. Refineries are typically large industrial complexes that consist of multiple connected units, each of which performs a specific task in the overall process. The purpose of an oil-processing plant is to convert crude oil into products that can be used for a variety of purposes, including transportation, heating, and manufacturing.