Pilling is the formation of small, fuzzy balls or clusters of fibers on the surface of a fabric. It occurs when loose fibers break free from the fabric and become tangled together, forming tiny balls or pills. Pilling is a natural and common occurrence, especially in fabrics made from natural fibers like cotton or wool, as well as in blends with synthetic fibers.

Several factors contribute to the development of pilling, including friction, abrasion, washing, and wearing. Over time, as the fabric rubs against itself or other surfaces, the fibers can loosen and accumulate to create these pill-like formations on the fabric’s surface. While pilling doesn’t necessarily affect the structural integrity of the fabric, it can alter the appearance and texture, making it look worn and less appealing.