I was having some trouble trying to figure out why $_SERVER['HTTP_REFERRER'] wasn’t working with php. I’m working in dreamweaver and when you type in ‘$_SERVER[‘ it will automatically populate your options. When you select “HTTP_REFERER” it will put in “HTTP_REFERRER” with that extra R. Very interesting bug…

Even more interesting, “REFERRER” is the correct way to spell it, I wonder why it is incorrect with PHP. Dictionary.com says

A misspelling of “referrer” which somehow made it into the HTTP standard. A given web page’s referer (sic) is the URL of whatever web page contains the link that the user followed to the current page. Most browsers pass this information as part of a request.