Scuffing a pole tip or basket lightly along the passing snow helps us balance. The feedback from the pole tip up our hand and arm helps us sense the inclination of our stance relative to the slope and adds rotational stability to our upper body.
I often see lesser-skilled skiers braced and stiff, their poles held aloft and pointing aft, as if to fend off attackers from behind. Their gloves may conceal a white knuckled grip, but their angst is revealed by their stiffly held aft-facing poles. Such skiers have yet to discover how dragging a pole tip can help them relax and ski more freely.
TIP - During each turn, drag the tip of the inside pole, being sure that the inside hand is well away from the torso, perhaps half an arm length towards the inside of the turn. Sensations up through your inside hand and arm then provide useful information for balancing purposes.
Dragging poles in various ways are common during skill building drills as well. For example, drag the tip or your outside pole to help develop skiing-purposed bending at the hip joint; this encourages an outward angle of the legs with respect to the torso, creating the classic 'racer' look. Or, whenever you are attempting a drill that challenges your balance, try dragging both poles, baskets beside boots.
Better balance allows relaxation, which facilities dynamic skiing. Generally, keep the hands high enough that the baskets brush the snow beside or just behind your boots, and otherwise relax the upper body and arms as much as possible without compromising the structure of your stance.
Keep the tip of the inside pole in contact with the snow throughout the turn for best results.