mod_perl is an optional module for the Apache HTTP server. It embeds a Perl interpreter into the Apache server, so that dynamic content produced by Perl scripts can be served in response to incoming requests, without the significant overhead of re-launching the Perl interpreter for each request. As Lincoln Stein defined mod_perl in his words:

mod_perl can emulate a Common Gateway Interface (CGI) environment, so that existing Perl CGI scripts can benefit from the performance boost without having to be re-written.

Unlike CGI (and most other web application environments), mod_perl provides complete access to the Apache API, allowing programmers to write handlers for all phases in the Apache request cycle, manipulate Apache's internal tables and state mechanisms, share data between Apache processes or threads, alter or extend the Apache configuration file parser, and add Perl code to the configuration file itself, among other things.

Mod or mods may refer to:

Perl is a high-level, general-purpose, interpreted, dynamic programming language.

Though Perl is not officially an acronym, there are various backronyms in usage, such as: Practical Extraction and Reporting Language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular amongst programmers. Larry Wall continues to oversee development of the core language, and its upcoming version, Perl 6. Perl borrows features from other programming languages including C, shell scripting (sh), AWK, and sed. The language provides powerful text processing facilities without the arbitrary data length limits of many contemporary Unix tools, facilitating easy manipulation of text files. Perl gained widespread popularity in the late 1990s as a CGI scripting language, in part due to its parsing abilities.

In addition to CGI, Perl is used for graphics programming, system administration, network programming, finance, bioinformatics, and other applications. Perl is nicknamed "the Swiss Army chainsaw of scripting languages" because of its flexibility and power. In 1998, it was also referred to as the "duct tape that holds the Internet together", in reference to its ubiquity and perceived inelegance.