Confused: "public directory" and "Public accessable"

How do you determine (or what is) the "public directory" or "public accessable" area of site? My initial thought was that the "html" dir on my hosted site was the "public accessable" dir but then doesn't my "cgi-bin", "stats" and other dirs have to be "public accessable also"?

Since I have a hosted site isn't my entire "home" dir considered to be a "public directory" or "public accessable". (with accessability being determined by permission settings, htaccess, etc, etc,)