Artery
The aorta is the main artery in the human body.  It starts in the left ventricle of the heart, which is full of blood that just picked up oxygen in the lungs.  (This is called oxygenated blood - meaning it has a lot of oxygen in it.)  The left ventricle pumps this oxygen-rich blood out through the aorta.  The aorta brings this blood to every organ in the body.