Playing cards and similar paper objects have very little mass and are not very aerodynamic except under certain circumstances. Simply throwing a card with no technique (that is, applying lateral speed only) usually will result in it fluttering about and falling to the ground. Achieving accuracy, distance and force with a card requires giving it both lateral speed and angular momentum (i.e. "spin") along its z-axis. The spin creates gyroscopic stabilization so that the card's flat profile remains mostly parallel to the direction of travel and thus suffers the least possible air resistance.