A search-engine-friendly URL (SEF URL) uses a meaningful path instead of a collection of technical parameters. Joomla provides SEF routing to make website addresses easier to read and manage.
Alias, slug and route
An alias is a textual identifier for an object such as an article or menu item. A slug usually refers to an object-related part of a path. Routing translates a request into the component and page to display. An alias alone does not determine a complete Joomla URL: menus, categories, language and component rules also matter.
Joomla settings
SEF and URL rewriting are related but separate settings. SEF produces readable routes, while rewriting can remove index.php when the web server is configured accordingly. Apache typically uses mod_rewrite and .htaccess rules, while Nginx requires its own server rules.
Before enabling rewriting on a live site, check hosting support and guidance for the installed Joomla release. Keep a way to restore the previous configuration.
Changing URLs
Changing aliases, reorganising menus or altering routing rules can change published addresses. Map old URLs to new destinations, configure redirects and update internal links and the sitemap.
A concise URL is useful, but including words in a path does not guarantee search rankings. Assess the consequences before changing stable addresses for cosmetic reasons.
Summary
SEF URLs make a Joomla site’s structure clearer. Reliable configuration requires consistent routing, suitable server rules and redirects from old addresses.