Pod::Simple is a Perl library for parsing text in the Pod ("plain old
documentation") markup language that is typically used for writing
documentation for Perl and for Perl modules. The Pod format is explained
the perlpod manpage; the most common formatter is called 'perldoc'.
Pod formatters can use Pod::Simple to parse Pod documents and render them
into plain text, HTML, or any number of other formats. Typically, such
formatters will be subclasses of Pod::Simple, and so they will inherit its
methods, like 'parse_file'.
If you're reading this document just because you have a Pod-processing
subclass that you want to use, this document (plus the documentation for
the subclass) is probably all you need to read.
If you're reading this document because you want to write a formatter
subclass, continue reading it and then read the Pod::Simple::Subclassing
manpage, and then possibly even read the perlpodspec manpage (some of which
is for parser-writers, but much of which is notes to formatter-writers).