The three main components of every irrigation system are the controller, station-control valves, and sprinklers. The controller is the brain of the system; it tells the control valves when and how long to supply water to the sprinklers. The sprinklers direct and control the water applied to the lawn and plants. Each valve controls a specific group of sprinklers called a “watering zone.” The stations are generally laid out and installed according to the type of plant materials to be watered, the location of the plant within the landscape and maximum amount of water that can be supplied. Each valve is connected to a numbered terminal within the controller, identifying it as “zone 1”, “zone 2”, etc. The controller operates the valves in order, one at a time. In other words, one zone waters completely before another zone turns on. This is called a watering cycle. The information stored in the controller memory determines when and how long each zone will water.