Blood pressure is the force of the blood pushing against the walls of the arteries. Blood pressure is typically recorded as two numbers, written as a ratio. The top (and higher) number, or systolic, which is also the higher of the two numbers, measures the pressure in the arteries when the heart beats (when the heart muscle contracts). The bottom (and lower) number, or diastolic, measures the pressure in the arteries between heartbeats (when the heart muscle is resting between beats and refilling with blood). The ideal range is more than 90 over 60 (90/60) and less than 120 over 80 (120/80).