Wool is a sheared animal product and constructed of protein. The fibers are naturally covered with tiny overlapping scales and under a microscope would resemble a pinecone, where the scales are only attached at one end. Other yarns differ in that they can be plant based (cotton) or man-made (acrylic). Merino wool is probably one of the most common wools found in many US stores. It comes from a sheep and is very soft. There are hundreds of breeds of sheep and each breed produces a different type of wool in terms of the crimp, which is the waviness and the staple, which is the average length. Reading the label will usually say Pure Virgin Wool and lead you to more specifics. Popular wool doesn't all come from sheep however, it can even come from a LLama! Mohair is from an Angora Goat. If it is Kid Mohair, it is the softest. Many stores sell a blended yarn 85%Wool and 15% Mohair- this makes a furry and shiny type of scarf. Cashmere is from Central Asian Goats- it is very soft and light weight. Since it is delicate, I use Cashmere blends in my gurglefish crochet scarves. The blends with Acrylic and Nylon add strength and durability to the scarf. Angora is the hair of Angora Rabbits. There are blends of Angora and wool which also produce a wonderful scarf. The Angora, like the Mohair, will shed. Alpaca is also widely available and one of my favorites producing a fluffy scarf with a beautiful drape. I really enjoy the scarves I've crocheted with it- it does have a little odor when it gets wet as most wools do. All wool scarves need to be hand washed in cold water and lay flat to dry or dry clean, unless it is a blend or it is treated, and it will say Superwash or Machine Washable on the label. The little overlapping scales of the fiber are heat and chemically treated not to absorb the water and cause the wool to shrink. If you are sensitive to wool, please check mydescriptions, as I give the percentage of wool and add details about the acrylic and organic yarns. Thanks and please visit my scarf store. Also see my blogs!