“Site” Documentation

I see references to the concept “site” (i.e. $current_site) in the code and can see a database table for to store “site” information. It appears that one can create multiple sites, where each site may have many different blogs.

I have searched quite a bit but cannot find any decent documentation related to creating new a new “site” and how all this works.

I am interested in knowing the preferred manner of creating a new site and if one can have site specific categories that are not accessible by other sites. Also, can we create site specific “Site admin” users.

If anyone knows of any documentation, please let me know 🙂

Thanks

Jim