Correct me if I am wrong but if you see a ? in a URL then it means the following are arguments for PHP or whatever language the developer/server is using. At least in PHP those are GET arguments and I was under the impression that you are not be able to do that in HTML or CSS. I know that by having it will not break the web address but I'm more so wondering why. Why are there ? arguments on .html/.htm files if you can't include any dynamic page code (except CSS percentages)?
Also let me know if this is a stupid question and I'll get it out of everyones way! :-P