Wool is the most popular and versatile fabric choice in men's suiting. Wool's quality is determined via a thread count or it's 'super' number. The most common are super 100's, 120's, 140's, 150's and 180's. The higher super number the finer the wool, this is from the high level of combing and twining of the wool before it is woven.
A wool material at the super 120's level provides a perfectly balanced suit between comfort, wrinkle resistance, fabric durability and longevity of use. Wools best feature is it's breathability and moisture absorption, so suiting up in summer time won't be as heated.
100% cashmere is a very luxurious fabric, like most luxurious items, there is usually a downside or tradeoff. 100% cashmere can carry a slight sheen and is not as wrinkle resistant as wool. It is a common fabric in Italy over Western cultures.
A wool/cashmere fabric however carries the benefit of both. Wools great qualities are combined with a soft, luxurious fabric providing a variation in texture to the usual 100% wool suit.
Polyester was developed in 1941 by two British chemists as a synthetic alternative to pure wool and it revolutionized the textile industry. This cheaper alternative to wool doesn't crinkle much given its synthetic make up. On the downside it traps heat significantly and can carry a shiny look. A wool/polyester blend has an advantage for frequent travellers where your suit will arrive fresh and relatively non crinkled. For more tips about travelling with your suit see our article Travel in Style. (Attach link for article)
Cotton has been a dress textile for over 8000 years given its great properties. As a fabric it is very durable and flexible in its weave and texture. Like wool, it breathes very well and is great with moisture control compared to other common fabrics. It is a perfect light material for spring, summer and fall.
The cost of wool is most commonly attributed to the width of the individual fibres. Simply put, the narrower those fibres are the more expensive the fabric. The width of these fibres is measured by micron numbers or more commonly by 'Super' numbers.
Now just because higher-grade wool is more expensive, does not mean that the fabric will make a good 'every day' suit. The finest Super fabrics are often too delicate to stand up to ordinary wear and should only be reserved for special occasions.
Now you know what is what in the world of suiting textile fabrics - before you buy, consider the requirements of the suit and which fabric will be the most appropriate.