Blood pressure is, quite literally, the pressure of blood as it flows through arteries in the body. Although a certain minimum blood pressure is required for normal function, usually low blood pressure is associated with good health and longevity. Blood pressure that is above the normal range can be associated with various health risks including heart attack and stroke.

Blood pressure can be influenced by a variety of factors, which can be transient or long-term. Stress, excitement and physical exertion typically raise blood pressure, as blood is pumped faster through the body; blood pressure may fall during subsequent relaxation. Smoking cigarettes or drinking coffee may raise blood pressure for as long as the drug (nicotine or caffeine) is in the body. Obesity, high levels of cholesterol, and diabetes all tend to raise blood pressure. Atherosclerosis, a buildup of cholesterol and calcium deposits inside the artery, narrows the passageways through which blood can flow, increasing the pressure and possibly reducing the volume of blood that can pass through the artery.