Galaxy phones have had a heart rate monitor since the Galaxy S5. The S9 adds a blood pressure reading. They call it "heart load factor." This is a wellness feature to provide an idea of your blood pressure, but Samsung isn't making any medical claims. You'll still need to consult your doctor for medical advice, or for monitoring a condition.

In addition, Samsung has partnered with UCSF to share your blood pressure information, and can monitor your stress levels to give you guidance for lowering your blood pressure.

Go to Samsung app folder > Samsung Health > tap HLF.