I have taught several Perl courses in the past and had used both the "Programming Perl" and "Perl in 21 Days" books for my courses. I have since switched to using "Core Perl" for my Perl courses. "Core Perl" is concise without being terse, well organized, and very thorough in its coverage. This book can be useful to both beginning and advanced Perl programmers. In addition to Perl, the book covers the DBI interface, CGI programming, Mason, and mod_perl, so it is perfect for people that are looking to Perl for building web applications. If you want to learn Perl, or extend your current Perl knowledge, this is the book to get.