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 pipeline fitting with one inlet and two outlets, or two inlets and one outlet. It comes in T and Y configurations, with both equal and unequal diameter outlets, used at junctions where three pipes, either identical or different, converge. The primary function of a three-way is to alter the direction of fluid flow.