Blood pressure is essential to life; we wouldn’t be alive without blood pressure. The reason for this is that blood pressure moves blood through your body, supplying all your organs with nutrients and oxygen. However, when blood pressure is too high or too low, you can experience serious health problems. 
In short, blood pressure is the force of blood against artery walls. So, when your heart beats, it pumps blood through a network of blood vessels, the arteries. As the blood is being pumped through the arteries, it pushes against their walls. When the muscles of your heart contract and push blood through your arteries, your blood pressure goes up. If the muscles relax, your blood pressure goes down. Hence, with each heartbeat, your blood pressure will increase to a maximum level and then decrease to a minimum level. A normal blood pressure is important, as abnormalities can have grave consequences.
