Self Service Portal - what is it and where is it?

Self Service Portal - what is it and where is it?

A few questions about the self service portal:

Is this portal available to people who aren't logged in? I.e available to the public to browse?
If it's public access, whats the URL to access it?
And where can I configure it per instance, I've been reading about widgets, but I cant find any of this.

                  New to ADSelfService Plus?