Hypertension, commonly known as high blood pressure, is a chronic medical condition characterized by elevated pressure in the arteries, which can lead to increased strain on the heart and blood vessels. Blood pressure is measured as the force exerted by blood against the walls of the arteries as the heart pumps blood throughout the body. Hypertension is diagnosed when blood pressure consistently remains elevated above normal levels over time. It is often referred to as the "silent killer" because it usually has no symptoms in its early stages but can lead to serious health complications if left untreated.