The pressure with which blood flows in the blood vessels is called Blood Pressure or BP. BP is measured using a special device called Sphygmomanometer.
When your heart beats, it pumps blood round your body to give it the energy and oxygen it needs. As the blood moves, it pushes against the sides of the blood vessels. The strength of this pushing is your blood pressure. If your blood pressure is too high, it puts extra strain on your arteries (and your heart) and this may lead to heart attacks and strokes.

What Causes High Blood Pressure?
The exact causes of high blood pressure are not known, but several factors and conditions may play a role in its development, including:
Smoking
Being overweight or obese
Lack of physical activity
Too much salt in the diet
Too much alcohol consumption (more than 1 to 2 drinks per day)
Stress
Older age
Genetics
Family history of high blood pressure
Chronic kidney disease
Adrenal and thyroid disorders