Complex or Novelty Yarns
Yarns can be created to have various visual effects. A novelty single yarn could have a slub, or an irregularity in the width and/or degree of twist of the yarn. This is often seen in natural fibres but can also be mimicked in manufactured fibres.
Ply yarns can have a base yarn, combined with one or more effect yarns. Examples of this are bouclé and chenille yarns.
Textured Yarns
Most manufactured fibres are thermoplastic and can therefore be heat-set into different textures such as crimped, looped and coiled yarns. These can create fabrics that are soft, warm, and bulky but still light weight.