What is the primary purpose of a coupling in plumbing?

The primary purpose of a coupling in plumbing is to join two pipes together. Couplings are essential fittings used to connect two sections of pipe, creating a continuous flow for water or other fluids. They ensure a secure and leak-proof connection, which is crucial in maintaining the integrity of a plumbing system. This connection allows for the extension of piping runs, enabling the transport of fluids over longer distances or around obstacles.

While couplings can contribute to flexibility in installation and facilitate disconnection in certain contexts, their fundamental role is specifically to unite different sections of piping. Couplings are not designed to regulate temperature; that function would be carried out by other components, such as valves or thermostatic devices. Thus, the correct answer highlights the primary function of couplings in a plumbing system.