Napping is the pulling-up of fibers from the base weave resulting in a fuzzy, raised surface. Nap-In or Nap-Out refers to the direction of the napping, either facing inside or outside. Although the fabrics are equally popular, Nap-In fabric outwears Nap-Out by providing greater abrasion resistance. Nap-Out styles are normally used in hot applications. Nap-In styles are normally used when abrasion is a concern.