Subsites
From Lanius CMS Wiki
Subsites are extensions of your parent site. They usually reside on the same server, and share the same root folder. More importantly, they share the domain name with the parent site.
Typically, a subsite can be identified by its subdomain, expressed in the form subdomain.maindomain.com.
Every subsite has its own administrative backend; when there are many subsites in your Lanius CMS installation it can be confusing to tell exactly what site you are working on. You can always look at the administrative page's banner, it will say Subsite if you are working with a subsite.
In Lanius CMS, subsites are managed through the System => Subsites Manager page of the administrative backend.

