HTML Upload MAX_FILE_SIZE does not appear to work

Question

I am wondering how is the hidden field named MAX_FILE_SIZE supposed to work?

Answer 1

Actually, it doesn't really work. You can find an explanation in one of the comments in the manual page: http://www.php.net/manual/en/features.file-upload.php#74692

Answer to updated question: the obvious difference is that server-side checks are reliable, client-side checks are not.