What is cool about cotton?

Answer 1

If you mean cool as in 'allowing heat to escape' cotton can be woven both very loosely and very thinly so as to provide many avenues for temperature equilibrium. In addition, cotton breathes, allowing moisture to escape, carrying away excess body heat as it evaporates.

If you mean cool as in 'fashionable', cotton is a very flexible product, lending itself to bright colors (it holds dyes well) and unusual designs and textures (cloth made from cotton is very strong, and able to stretch quite a bit before it tears).

Cotton is also a natural product, unlike Spandex or polyester, which means that it's more comfortable and less likely to cause an unwanted reaction, such as an allergy or a rash.