A “Christmas tree” is a term used in the oil and gas industry to describe an assembly of valves, spools, and fittings installed on the wellhead of a completed oil or gas well. It gets its name due to its resemblance to a decorated Christmas tree with multiple branches when viewed from a distance.

The main purpose of a Christmas tree, or tree,  is to control and regulate the flow of hydrocarbons from the well to the surface. It allows operators to monitor well pressure, perform well interventions, and inject fluids or gases if needed to enhance recovery. The tree also serves as a crucial safety barrier, as it contains valves that can be closed in case of an emergency or during routine maintenance to prevent uncontrolled release of hydrocarbons.