From Valve Developer Community
Automatic Category
Please do not manually add pages to this category
This category is automatically added by the {{Status}}
template.
If the page has been added to this category by a template, but does not show up, you can "Purge cache" this page.
This category indexes user pages that have {{Status|type=active}}
transcluded into them. For more info see Template:Status.
Preview
Active
This user is predominantly active and can frequently be seen making edits or creating new pages.
Pages in category "Active Users"
The following 2 pages are in this category, out of 2 total.