I think the PHP documention for $_SERVER['PHP_SELF'] could be written better. Why did the writers include this part (which this page mindlessly regurgitates verbatim): "The FILE constant contains the full path and filename of the current (i.e. included) file." I think the reason is the original author is trying to make a comparison, but not being explicit enough. I think he or she is saying $_SERVER['PHP_SELF'] vs. FILE are complimentary: If $_SERVER['PHP_SELF'] is referenced from an included file, it returns the path to the includING file. But if FILE is referenced from an included file, it returns the path to the includED file.