Do you remember how comfy it was when we wore socks in school? Since we're now grown ladies and don't wear those black leather school shoes anymore, we seldom use socks.
I wear footsies with low cut sneakers, booties, brogues/oxfords, and the like. It makes wearing those closed shoes comfortable at the same time they stay invisible, not ruining your get-up. I prefer the cotton type rather than the "stockings" material.
I bought this during my Korea trip last Aug (2009) from a side street vendor, similar to the ones we have here in the Philippines. I love it coz they have those anti-slip material that holds the socks in its place. It doesn't get removed from your feet when you walk. I'm pretty sure these are also available in the department stores here.