There are two versions of Perl under active development: Perl 5 and Perl 6. Confusingly, Perl 6 represents a completely new language, with a lot of carryover from previous versions of Perl but limited backward compatibility. Perl 5, on the other hand, is the direct descendant of previous versions of Perl and offers very good backward compatibility. In the future, it is probable that both Perl 5 and Perl 6 will be installed side-by-side on most Unix-like systems allowing users and admins the opportunity to select which version to run.