Three-way fittings, also known as pipe fittings three-way or three-way pipe fittings, and three-way connectors, are mainly used to change the direction of fluid flow and are applied at the point where the main pipeline branches off. They can be categorized by pipe diameter. They are commonly made from carbon steel, cast steel, alloy steel, stainless steel, copper, aluminum alloy, plastic, polytetrafluoroethylene, PVC, and other materials.

Three-way fittings are used for pipe joints and pipe connectors. Also known as three-way pipe fittings or three-way joints, they are used where the main pipeline needs to branch off.

A three-way is a type of industrial piping fitting with three openings: one inlet and two outlets; or two inlets and one outlet. It comes in T-shaped and Y-shaped configurations, with both equal and unequal diameter openings, used at junctions where three identical or different pipelines converge. The primary function of a three-way is to alter the direction of the fluid flow.