This book represents a system of theoretically-derived inherent laws of a special type of fibrous assembly, known as yarn. Structural approach has been the basis of this book. Each chapter of this book is started with definitions, terminologies and fundamental relations. Then the theoretical models are presented namely from the initial assumptions through the mathematical derivation to the final relations. Such theoretical results are mostly compared with the experimental results.

The topics on yarns include count, twist and diameter, number of fibres in cross-section, retraction and saturated twist, fibre helix, fibre migration, mass unevenness, hairiness, strength, fibre slippage, etc.