A tee fitting is a plumbing part that allows you to join pipes at 90-degree angles. They are shaped like a capital T, and come in various sizes, depending on your application.
The main purpose of a tee fitting is to either separate or combine the flow of a liquid running through the pipes. These are especially useful in houses with several rooms, which have isolated water needs.
Tee fittings therefore can be used to redirect water coming from a single source to several portions of the house. These are not just used in plumbing situations but in others as well, such as car engines and the internal cooling systems of modern computers.