B.30. Locales and Unicode
Locales tell Perl how things are done locally. For example, does the character æ sort at the end of the alphabet or between and Œ? And what's the local name for the third month? See the perllocale manpage (not to be confused with the perllocal manpage).
See the perlunicode manpage for the latest on how your version of Perl deals with Unicode. As of this writing, each new release of Perl has many new Unicode-related changes, but we hope things will settle down soon.