Summarize:

Woven rugs can either have heavy pile, thin pile, or no pile at all - it's just the density of the vertical fibers protruding from the rug. The direction that those fibers naturally lay is called the pile direction. To determine the pile direction, brush your hand along the rug. If you are brushing against the pile, you will feel resistance. Always dust or brush woven rugs in the direction of the pile. Stroking against the pile can cause softer wools to break.
Find the pile direction of your rug.