Blood pressure is a measure of the force that your heart uses to pump blood around your body.

Blood pressure is measured in millimetres of mercury (mmHg) and is given as 2 figures:

• systolic pressure – the pressure when your heart pushes blood out
• diastolic pressure – the pressure when your heart rests between beats

For example, if your blood pressure is "140 over 90" or 140/90mmHg, it means you have a systolic pressure of 140mmHg and a diastolic pressure of 90mmHg.

As a general guide:

• ideal blood pressure is considered to be between 90/60mmHg and 120/80mmHg
• high blood pressure is considered to be 140/90mmHg or higher
• low blood pressure is considered to be 90/60mmHg or lower