An alias in Joomla is a textual identifier for an article, category, menu item or another object. It can contribute to a human-readable page address.
How aliases are generated
If the field is empty, Joomla usually derives its value from the title. Manually entered values are processed to remove or transform unsuitable characters. Unicode alias mode permits characters from non-Latin alphabets. The resulting value therefore depends on configuration and component rules.
Relationship to a page URL
An alias is not the complete URL. Joomla routing also depends on menus, parent categories, language and router settings. Changing a published alias can change the address, so check incoming links and any required redirect from the old URL.
Prefer short, meaningful values. This site uses matching aliases for associated language versions, with Joomla language routes and record associations distinguishing the pages.