Loss of pile height from use, where the wool has been walked short or away entirely, typically in a hallway, entryway or other high-traffic path, and in a badly worn rug the foundation begins to show. Even wear across the whole surface is the normal pattern on an older rug and is what buyers look for, whereas patchy wear, with short or bare zones beside fuller pile, weakens those spots and makes further damage likely, which matters most for a rug meant for heavy traffic. Rotating the rug periodically spreads the wear. Wear alone does not date a rug, since some new rugs are finished low to look old and some antiques keep a full pile.