As the heart pumps blood around the body by contracting and relaxing, the blood inside our arteries creates pressure on the inside of our artery walls. When we have our blood pressure measured it is this force or pressure that is measured. It is written as two numbers for example: 120/70mmHg (millimetres of mercury). The top number is called the Systolic blood pressure, which is the pressure inside our arteries when our hearts are contracting squeezing the blood out. The bottom number is called the Diastolic blood pressure, which is the pressure inside our arteries when our hearts relax and fill with blood. Knowing what our blood pressure measurements are can help decisions about lifestyle.