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

A three-way is a type of piping fitting with three openings: one inlet and two outlets; or two inlets and one outlet. It comes in T and Y 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 fluid direction.