Mediawiki's url confusion

Hi everyone: I've been studying the codes of Mediawiki for some time. I'm convinced that the file "index.php" is the only entrance to the whole site. But I cannot help myself with the url pattern : /somepath_to_mediawiki/index.php/pagetitle. How can this kind of url be parsed to the file "index.php" and the "pagetitle" be parsed as params? Why the web server not go straight into path "index.php/" and look for the file named "pagetitle" ? My first post ^_^ .And,I'm not sure if this issue should be talked here^_^. thank you however~ Lamp Deng 09/07/23