what is tape yarn
Tape yarns are used for knitwear and typically formed by weaving or knitting. They are often made on circular knitting machines, giving them a tubular cross-section, in the form of a tape with a large width-to-thickness ratio.
This kind of yarns is flat and just like tape or ribbon and that is the reason why people call it tape yarn. Its flat nature character makes it possible to achieve a knitted pattern that could not be accomplished with other types of yarn like normal round yarn.