What do blood pressure numbers mean?

The two numbers that measure your blood pressure are written like a fraction: one number on top and one on the bottom -- for example, 128/82. The number on top is called the "systolic pressure." Systolic Blood Pressure measures the pressure inside your blood vessels at the moment your heart beats. The number on the bottom is your diastolic pressure. Diastolic Blood Pressure measures the pressure in your blood vessels between heartbeats, when your heart is resting.