The SubSite settings allow an editor to control how the public sees your web site, how the admin site behaves, which content features are available to editors, what custom metadata attributes are defined, and which editor is the overall SubSite owner.

How do I manage SubSite Options?
How do I manage SubSite Content Features?
How do I manage SubSite Metadata Attributes?
How do I manage SubSite Ownership?

Selecting a SubSite name enters the SubSite where an editor can manage folders, pages, and content objects.