Usually made from a blend of polyester and nylon, a microfiber cloth (sometimes microfibre) is a cleaning textile made up of ultra-fine fibers. These fibers, which can be 100 times finer than a strand of human hair, are highly absorbent. Furthermore, they're very soft, which helps protect sensitive products such as flat-panel displays from scratches when they're cleaned.
Microfiber cloths come in many shapes and sizes. The picture is an example of a microfiber cloth produced by Zeikos that is designed specifically for scratch-prone glass like camera lenses and some computer monitor surfaces.