You may see a strange looking pipe setup with a thing that looks sort of like a bell around your building. That contraption is called a PRV or Pressure Regulator Valve.
It may also be called a pressure reduction valve, water reducing valve or pressure reducing valve.
The water pressure coming from the street into a building is generally very high and needs to be reduced lower. High water pressure is not a good thing as it can cause premature leaks in plumbing pipes and plumbing fixtures such as sinks and shower faucets. Gaskets and seals can get work down faster with high water pressure. A pressure regulator helps prevent problems that causes high water pressure.