CPAN, or the Comprehensive Perl Archive Network, is a large repository of software and documentation for the Perl programming language. It contains thousands of modules and distributions that developers can use to enhance their applications, making it easier to find and share code. CPAN is organized into a structured directory system, allowing users to search for specific modules or browse by category. It also provides tools for installing and managing these modules, streamlining the development process for Perl programmers and fostering a collaborative environment within the Perl community.