Yarn is perhaps the most essential component of knitting and crochetingso how do you know which one is right for your special project. The fibre content of the yarn that's right for your project will likely be determined by its end use. Wool and silk yarns are great for warmththink sweaters, scarves and blankets. Use cotton yarns for durabilitygreat for fashion accessories, window treatments, and home dcor accents. A good rule of thumb is the more ornate the yarn, the simpler your projects pattern or shape should be. Novelty yarns like boucle, marled, or variegated are perfect for shawls and blankets whereas more classic, plain varieties like smooth plied yarn are great for more stitching techniques. Categorised by the thickness of the thread, yarn weights range from 0 to 7 or lace to jumbo. Use lighter weights (0-2) for socks and delicate baby apparel. Medium weights (3-4) are great for sweaters, scarves and light outerwear. Heavier weights (5-7) for best suited for blankets and rugs.