Hypertension is abnormally high blood pressure (140/90 -- "140 over 90" -- or higher). Where it has no know cause it is called essential hypertension. When a disease or other physical problem is the cause of high blood pressure, the condition is called secondary hypertension. Virtually all chronic hypertension is essential hypertension.
Hypertension (high blood pressure), is a major cause of stroke and a risk factor for coronary disease.
In 2001, approximately 27% of the adult population in the USA suffered from high blood pressure. Over 30 percent of those were unaware of their condition and less than 25 percent were taking medication to help lower their pressure.