Final answer:
Blood pressure is the reading of the pressure inside arteries.
Step-by-step explanation:
Blood pressure is the reading of the pressure inside arteries. Arteries are blood vessels that carry oxygenated blood away from the heart to the rest of the body. They have thick, muscular walls that help maintain high blood pressure. As blood moves from the arteries and into smaller blood vessels called arterioles, the pressure gradually decreases. Therefore, blood pressure is measured in the arteries, which are the blood vessels that have the highest pressure.