kaardenBefore spinning the wool is carded. The fibers are dientangled with a comb with steel points, or hand cards. This used to be the fruit of a plant, teasel, used as card. So you make a blanket or a sliver of wool and fibers all in the same direction, and also the last remnants of dirt are eliminated.
It can also be done with a (hand crancked or electric) drum carder with a rapidly rotating cylinder with steel or even a needle bed.

After carding, if any, can be spun directly. For a finer result still has to be combed.

The teasel was used mainly to comb wool fabrics waterproof. By laying all fibers in the same direction, you get a tile effect. Even in industrial applications teasels were still strung on steel rods for this purpose.