Plack
Plack is a Perl web application framework and toolkit that provides a standard interface (PSGI) between web servers and Perl web applications. It enables developers to write web applications that can run on various web servers without modification, similar to WSGI in Python or Rack in Ruby. Plack includes middleware components, utilities, and adapters to simplify web development in Perl.
Developers should learn Plack when building or maintaining Perl-based web applications, as it offers portability across different web servers (e.g., Apache, Nginx, Starman) and streamlines development with reusable middleware. It is particularly useful for modern Perl web frameworks like Dancer and Mojolicious, which use PSGI, and for deploying applications in diverse environments without server-specific code.