Hypertension is the term used to describe high blood pressure. Blood pressure measurements are the result of the force of the blood produced by the heart and the size and condition of the arteries. There are two types of high blood pressure: Primary (essential) hypertension In 90 to 95 percent of high blood pressure cases in adults, there's no identifiable cause. This type of high blood pressure, called essential hypertension or primary hypertension, tends to develop graduall