"You have high blood pressure, also referred to as hypertension, when it reaches dangerously high levels.Your blood pressure is determined by the volume of blood pumping through your arteries and the resistance the blood faces.Typically, the onset of hypertension takes several years. Most of the time, no symptoms are noticeable.Even in the absence of symptoms, hypertension can damage your blood vessels and vital organs, especially the kidneys, heart, brain, and eyesIt's critical to identify early. Checking your blood pressure frequently can help you and your doctor notice any changes..