A paintball Hopper is a device which feeds paintballs into a paintball gun’s breech.  A Gravity Feed Hopper uses gravity which naturally drops paintballs into the paintball gun.  An Electronic or Motorized paintball hopper uses a motor to physically push or pull paintballs into the gun.  A paintball hopper in the olden days was also called a “loader” becuase it loaded the paintballs into the paintball gun.