Top Web Sites Running Linux

There is really little

There is really little difference between Linux and Unix (even though Linux was written from scratch). Linux, BSD, Mach etc are all flavors of Unix. If there was no Unix (God bless Ritchie and Thompson), there would be no Linux or IOs today.

Do not club Unix and Windows together. Most top websites using Windows belong to Microsoft. Outside of Microsoft, not many would consider Windows for a top website.

Almost all top websites use some flavor of Unix. You forgot Amazon, E-Bay and many more ...

According to the tool I was

According to the tool I was using (netcraft) Amazon and Ebay could not be determined to be running Unix. Their status is simply unknown. If they are in fact running a flavor of Unix, I stand corrected, but your statement that "almost all top websites use some flavor of Unix" is simply incorrect, unless you are considering Linux a flavor of Unix, which I do not. Of course it is a descendant of Unix, but the point of my post was to show the popularity of this typically-free, open source OS, and how top billion-dollar web companies (like Google and Facebook) also rely on it (rather than paying for, say, Solaris, or some other Unix variant).