Perl 1.0 came out in 1987. In the decades since then, The language has gone from a simple tool for system administration somewhere between shell scripting and C programming (Perl 1) to a powerful, general purpose language steeped in a rich heritage (Perl 5) and a consistent, coherent, rethinking of programming intended to last for at least another 25 years (Perl 6).

Even so, most Perl 5 programs in the world take far too little advantage of the language. You can write Perl 5 programs as if they were Perl 4 programs (or Perl 3 or 2 or 1), but programs written to take advantage of everything amazing the worldwide Perl 5 community has invented, polished, and discovered are shorter, faster, more powerful, and easier to maintain than their alternatives.

Modern Perl is one way to describe how experienced and effective Perl 5 programmers work. They use language idioms. They take advantage of the CPAN. They're recognizably Perlish, and they show good taste and craftsmanship and a full understanding of Perl.

You can learn this too, whether you've dabbled with Perl for a decade or someone just handed you this book and said "Fix this code by Friday."