I sometimes find it difficult to decide which is the appropriate site to ask a question. For example, I have a question today about choosing a web platform for a new UNIX server we are purchasing. Since it's not a "programming" question exactly, it's probably off-topic for Stack Overflow, but I cannot decide where it should be asked. Possibilities include SuperUser, UNIX, and WebMasters.
I know I can visit each site and read the "About" page, but is there a page somewhere that describes the goals of all the Stack sites, like a "Table of Contents"?
I do realize that my question about a web platform might not be appropriate for any of the sites (since in some ways I'm asking for advice). I'll check the rules first.