What is hypertension?

High blood pressure. For an adult, a blood pressure of >135 systolic (the top number) or >85 (the bottom number), when taken at rest and averaged over multiple readings at different times, is considered to be high or "hypertensive.".
Blood pressure. Hypertension is when the blood pressure exceeds 140/90 mmhg for a significant part of the day. If untreated, these people have an increased incidence of atherosclerotic disease, heart attack, stroke and kidney failure.