Thread:Project:Support desk/Changing page link format in Wiki v.1.21.3

I've just set up a stand-alone Wiki (MediaWiki v.1.21.3, PHP 5.3.10-1ubuntu3.9 (fpm-fcgi), MySQL 5.5.27-log) and noticed that its page paths have a format different from what I'm used to seeing on Wikipedia or here. Rather than using slashes as separators, e.g.: https://www.mediawiki.org/wiki/Project:Support_desk, pages in my Wiki have paths with index.php?=title strings in them, like: http://xyz.org/index.php?title=Help , which looks untidy and makes wikilinking less obvious to me. How do I switch over to the format I'm more accustomed to, with slashes as separators?

Regards,