This book deals with the importance of textile testing and yarn properties testing. Textile testing is the application of engineering knowledge and science to the measurement of the properties and characteristics of, and the conditions affecting, textile materials. It involves the use of techniques, tools, instruments and machines in the laboratory for the evaluation of the properties of the textiles. Testing is conducted for check the quality of raw materials, monitoring production, assessing the quality of the final product, investigation of faulty products, new product development, and standardization of testing. Textile testing is a vital basic tool during the processing of a textile raw material into the product. It also helps the distributors and consumer to determine the end product¿s quality. So, textile testing refers to the procedures adopted to determine quality throughout the textile product chain. It can be summarized as the application of engineering facts and science to determine the quality and properties of a textile product.