The brains of your irrigation system controlling the valves to allow water to go to different areas (zones) of irrigation. Typically they are located in a garage but sometimes you'll find them outside!
Found in the ground, irrigation valves are operated by your Controller/Clock to open and close to allow water to different areas of your lawn. You have one valve per zone.
The sprinkler heads that pop up and rotate.
This sprinkler head pops up and remains stationary while watering your lawn