An arrow’s centre of mass (CoM) is its balance point. Usually this will be forward of the centre of the shaft, due to the point being a significant portion of the arrow’s mass. Heavier points mean that the CoM is further forward.
An arrow also has a centre of pressure (CoP) or aerodynamic centre. This is the place on the arrow where the aerodynamic pressures are balanced. Usually this will be rear of the centre of the shaft, because of the aerodynamic properties of the fletches.
For any practical arrow, the CoM is in front of the CoP. If the CoM was behind the CoP, the arrow would turn around after leaving the bow and fly nock
