Blood pressure (bp) is defined as the force in the arteries when the heart beats (systolic pressure) and when the heart is in between beats (diastolic pressure). It's measured in millimeters of mercury (mmHg). The measurement is written one above or before the other, with the systolic number on top and the diastolic number on the bottom.

Hypertension is defined in an adult as a blood pressure greater than or equal to 140 mmHg systolic pressure and greater than or equal to 90 mmHg diastolic pressure. Increased pressure in blood vessels directly increases the risk of heart attack, coronary heart disease and stroke. Hypertension affects millions of adults, and can be a genuine health concern.

Hypertension can occur in children or adults, but it's more common among people over 35. It's particularly prevalent in African-Americans, middle-aged and elderly people, obese people, heavy drinkers and women who are taking birth control pills. It may run in families, but many people with a strong family history of hypertension never have it. People with diabetes mellitus, gout or kidney disease are also more likely to have hypertension.

Some people can have hypertension for years without knowing it. The only way to know if you have hypertension is to have your blood pressure checked. According to recent estimates, one in four U.S. adults has hypertension, but because there are no symptoms, nearly one-third of these people don't even know they have it. This is why high blood pressure is often called the "silent killer."

A single reading showing high blood pressure doesn't mean you have hypertension, but it's a sign that you need to watch it carefully. High blood pressure is typically only diagnosed after consistent or consecutive high readings. Even If your blood pressure is normal, get it checked at least every two years. If your blood pressure is near the top of the normal range, or if you have a family history of high blood pressure, you're at higher risk. Your doctor will tell you how often to have it checked.

If you think you have high blood pressure but you have not talked to your doctor about it, then it is important that you schedule an appointment. You need to know if you have it and if so, what stage you are at so that you can make the necessary changes to better your health. Hypertension is usually divided into four stages: prehypertension, stage 1 hypertension, stage 2 hypertension, and hypertensive crisis.