Exercising a valve is important. Valves are a key part of every house’s plumbing. I am referring specifically to your water lines. There are three valves pictured here. There are two ball valves on the left. The far-left valve is open with the handle in line with ball valve body. The other ball valve is closed with the handle perpendicular with the valve body. The far-right valve is a gate valve. The valve is opened by turning the round handle counter clock-wise and closed by turning clock-wise when looking at the top of the valve. Home owners should know where the water supply valve, hot water heater supply valve and any water filtration bypass valves are located. Exercise (close and open) these valves at least once per year, so when time comes that you need to use them, they are not stuck open without getting ugly. Kind Regards, Mike