Hypertension is a fancy-schmancy word for high blood pressure. It is considered hyper tension when your bp (blood pressure) is 140/90. If your heart pressure is between 120/80 and 139/89 it is considered prehypertension or that you are likely to develop high blood pressure. High blood pressure is dangerous because it causes the heart to work too hard and can lead to serious diseases such as heart attack or stroke. It also leads to the hardening of the arteries- (arthroscelorosis). It can also lead to other conditions such as kidney disease and blindness. Unfortunately there are no symptoms to this condition, but research shows that 90% of the population experiences hypertension once during their lifetime. Hope this helps!