About
The slug is a custom page path that permits to customize at will your page url (if you choose to).
Example
With the slug value
the:slug:that:you-have-chosen
and a page url configuration of slug, the url of your page will be:
http://example/com/the/slug/that/you-have-chosen-pageid
where pageid is a short page id encoded
Management
Modification
You can modify it via the metadata manager
Configuration
To be used, the page url configuration should be on one of the available slug configurations