index.php vs index.php?

[eluser]Beginers[/eluser]
Hi guys im just curious about this two index.php and index.php?
at first i used the index.php but this does not load properly the image so i add ? after index.php so it works properly but then i dont want to show index.php? in the url cuz i looks silly in the url so i remove it using htaccess. after removing the index.php? in the url my page again does not load properly the css file why? pls help.