Wool,which is the main non-synthetic carpet fiber, is also the most expensive carpet fiber. It is a difficult fiber to clean and stains easily, but it has a soft, luxurious feel and is very resilient.

You can also purchase blends of multiple fibers, or acrylic, which is the synthetic version of wool (though it is less luxurious than is wool).

Padding: The backing on the fibers can reduce noise and add insulation to your home. The higher the density of padding, the better the padding is; in other words, the harder it is to compress the padding in your hand, the better the padding is.

Pile Weight and Height: Pile weight refers to the weight of the yarn in every square yard while the term “pile height” refers to the height of the yarn (whether loop or cut-pile). In general, a heavy pile weight and a longer pile height make for a better carpet, but fibers of varied height minimize footprints better than do uniformly tall fibers.

Twist: Twist refers to the way in which the fiber is spun into yarn. The tighter the twist, the more durable the carpet. Cut-pile carpets should be heat-set so that they retain their twist over time.

Density: There are two types of density: the amount of pile in the carpet and the amount of tufts in the backing. In both cases, high density is better. To test tuft density, fold back the carpet and see if you can see the backing; the less you can see it, the better.

Branded Fiber: Branded fibers have been treated with stain and soil repellant before they were attached to the backing. Consequently, they better repel stains than do fibers that only had repellant sprayed on top of them