Your question relates to a subject which can sometimes be as complicated to comprehend as buying a car.

Here are a few simple rules that should be used while shopping:

• Carpet is sold by yarn weight (ounces of yarn per square yard), density (number of tufts per inch in each of two directions), and yarn type (nylon, rayon, wool, etc.).
• The Federal Housing Administration (FHA) requires carpet to be a minimum of 24 ounces in weight for any home which it finances. Other factors such as yarn length, yarn twist, and backing material can also alter quality as well as price somewhat. A good yarn weight will run between 30 and 40 ounces with higher end carpets running in the 50 to 60 ounce range. Tuft density in most carpets will run about 10 to 11 tufts per inch. More tufts per inch make for a "tighter Knapp", or more dense carpet. Low-cut pile carpets will be lighter than high-cut pile carpets when the density of the two is equal.
• Nylon is one of today's best buys. Nylon, and a factory applied coat of Scotch Guard, has proved to be a winning combination. Wool is also very nice (and easy to clean too), but wool can be pretty expensive.

Bottom line -- Look for a Scotch Guarded nylon low-cut pile carpet assembled at 10 to 11 stitches per inch that weighs about 40 ounces per yard. It will feel very dense to the touch, resist abuse well, and last for years.

The pad we recommend is a 1/2 inch thick, 7 pound weight, rebond style. Use a jute pad if you have a concrete floor with radiant heating.