The ideal blood pressure for a healthy adult is 120/80mm Hg. This can be measured using a sphygmanometer, which displays the systolic pressure over the diastolic pressure. Blood pressure is a quantitative measure in mm Hg (millimeters of mercury) for the amount of pressure that is exerted on to the walls of the blood vessels when the blood is forced through. The blood vessels create a resistance to the flow, thus creates a pressure resistance.
When an individual's blood pressure is too high it is known as hypertension.
When an individual's blood pressure is too low it is known as hypotension.