mod_perl integrates the complete Perl interpreter with the Apache web server. With mod_perl, programmers can take existing Perl CGI scripts and plug them in, usually without making any source code changes. The scripts will run exactly as before but many times faster. In addition, mod_perl offers a Perl interface to the Apache API, allowing full access to Apache internals, so that programmers can control every aspect of the Apache server.
mod_perl Pocket Reference is a concise, conveniently formatted reference to all mod_perl features used in day-to-day mod_perl programming. This small book covers functions as well as configuration directives that help maximize the effectiveness of the mod_perl Apache module.
Andrew Ford is an author and consulting computer programmer who has been involved with the Web since its early days. His book Spinning the Web was the first on publishing with the Web. He also maintains a collection of quick reference cards at http://refcards.com.
Comments about O'Reilly Media mod_perl Pocket Reference:
This little guidebook goes out of its way to say what it isn't -- "this is not meant to be a guide to so-and-so" -- and yet it does an excellent job of giving an overview of mod_perl, cgi, and apache, including the role and functionality of each and how you can leverage them. Samples of some of the code would be appreciated, but then the format of the book doesn't really allow this, and that's okay -- you can turn to more thorough manuals for that.
For a quick introduction to the subject, an overview of why you should be using mod_perl instead of standalone scripts, and a pocket-sized pamphlet that you can turn to for reference once you have more experience with the material, this book should be a fine choice.