Hypertension is high blood pressure. Blood pressure is the force of blood pushing against the walls of arteries as it flows through them.
Blood pressure which remains consistently high and not just once twice is termed hypertension. Persistent hypertension is one of the risk factors for stroke, myocardial infarction, heart failure and arterial aneurysm, and is a leading cause of chronic kidney failure.
In most cases the cause for high blood pressure is not known but familial heredity factors, stress, kidney pathology and hormonal imbalance are some causes. More than 80% of hypertension is "Essential hypertension" for which no cause can be found. Normal blood pressure is measured in two parameters. One is systolic (upper) and second is diastolic (lower). Systolic tells about the condition of the heart while the diastolic tells about the force that the heart has to work against. 120/80 mm of mercury, is the normal reading. But a lot of doctors consider 140/90 mm of mercury as within normal range in young adults.