Blood pressure is the pressure of blood in your arteries (blood vessels). Your blood pressure is recorded as two figures. E.g. 120/80 mmHg. The 1st number is systolic pressure. It is the pressure in the arteries when the heart contracts. The 2nd number is diastolic pressure. This is the pressure in the arteries when the heart relaxes. When the pressure is 140/90 mmHg or more and it is sustained it is called the high blood pressure.See more..