Formal & Nylon Socks men's 

Nylon dress socks are generally thin to sheer, not all nylon socks are sheer, be sure to read description it does mention weather they are sheer or not sheer.

Nylon socks became popular around the turn of the century with the advent by dupont of nylon. Before that most socks were hand knitted or were considered a luxury item.

Why nylon socks and not cotton?  

Many people still want nylon socks because of the weight nylon socks are generally lighter than cotton socks and stay up longer because of the elastic properties of nylon. Nylon dress socks also do no shrink after repeated washes and do not fade and have a certain shine and luster to them that cotton does not. (mercerized cotton is the shinny version of cotton)  ofcourse, rayon, polyester all fall under the nylon umbrella they are all systhetic and man made. Rayon socks are usually the one with the most shine and luster and great for ultra formal evens. Sheer nylon dress socks by stacy adams are also used for ultra formal events where a tuxedo is required