Microfiber is synthetic fiber finer than one denier or decitex, ie even finer than a strand of silk or a human hair. The most common microfibers are usually made of polyester, polyamides (e.g. nylon, Kevlar, nomex, etc), polypropylene or a combination of them. In fact, the raw material is often chosen based on the final application and the expected features like smoothness, water adsorption or repulsion, electrostatic properties, filtration, etc.
Microfibers are used to produce mats, knits and weave textiles, apparel, furniture, filters and cleaning products.
They are also an excellent choice for athletic cloth manufacturing due to their good wicking and elasticity. On the other hand, they can be used as underwear cloth because of their smoothness.
If you have a closer look at their cross-section of these fibers, you would realize the reason behind their good performance in cleaning. A microfiber fiber cross-section looks like an asterisk whereas cotton is a circle.
Another advantage of microfiber rather than cotton, which is very important for cleaning, is the absence of lint.
When you clean a cloth made of microfibers, there is no need to be worried about its pilling getting on the rest of the clothes. It is better not to use machine-washing as much as possible and dry them according to the cloth tag to keep their quality.
As mentioned microfibers are incredibly finer than a strand of silk or human hair, so they do not scratch the surfaces like eyeglasses, cars, windows, etc.