Apache runs on Linux as well as Windows (and some other OSes). It's just rare to find a Windows based host use it.
.htaccess is Apache specific, though IIS has similar capabilities these days from what I've read (different code though). There's also the Litespeed web server, which aims to be a drop in replacement of Apache (with a lot better performance, or so they claim), and it advertises itself to be .htaccess compatible.
.htaccess is a file you can create and place in the folder you want it to regulate.