Pipe fittings and fixtures are required to join pipes together, change pipe directions, and connect pipes to other systems. They must be durable, easy to install and repair, and made from standardized components. Common types of pipe fittings include bends, tees, crosses, reducers, elbows, couplings, nipples, and valves. Fixtures include items like showers, pillar cocks, and unions that interface directly with the piping system. Proper selection of pipe fittings and fixtures allows for effective distribution of fluids throughout a piping network.