Knitting needles come in a variety of materials, each offering a different feel. Bamboo and wood needles grip the yarn, which slows the work and helps beginners control loose stitches. Metal needles are slick and fast, favored by experienced knitters working in fine yarns or large projects. Plastic needles are inexpensive and lightweight. Needle size refers to the diameter of the needle, which directly affects stitch size when paired with a given yarn. Sizes are expressed in US numbers, UK numbers, or metric millimeters; for example, a US size 8 is equivalent to a 5 mm needle.
Beyond straight needles, knitters use circular needles, which join two tips with a flexible cable and can be used for both flat knitting and knitting in the round. Circular needles support heavy projects by distributing weight across the cable. Small-circumference work, such as socks, can be done on double-pointed needles (DPNs) or with a long circular needle using the magic loop technique. Crochet hooks, by contrast, are single tools ranging from very fine thread hooks to jumbo hooks for thick yarn. Hook materials mirror those of needles, and ergonomic hooks with cushioned grips help reduce hand fatigue during long sessions.
Yarn itself is described by weight and fiber. Yarn weight categories range from the thinnest, lace, through fingering, sport, DK, worsted, aran, bulky, and finally super bulky. Fingering weight is thin and well suited to socks, lace, and lightweight garments; worsted weight is medium and the most commonly used; bulky weight produces fast, warm projects. Fiber content shapes the feel and behavior of the finished fabric. Wool from sheep is warm, elastic, and traditional, with merino being a notably soft, fine variety. Alpaca is soft and warm but less elastic, while cashmere is luxuriously soft and mohair from Angora goats is famously fluffy. Plant fibers include cotton, which is cool but prone to stretching, and linen, which is durable and softens with use. Silk offers luster and strength with low elasticity, and acrylic is a synthetic that is durable and easy to care for but less breathable. Yarn preparation also matters: worsted-spun yarns are smooth and sleek, while woolen-spun yarns are fuzzy and lofty.