A good way is to use the POD system:

=pod

die "testing";

=cut

=for comment

die "testing";

=cut
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Also note - any decent code editor should enable you to throw a # in front of a selected set of lines very easily.

I would add to this thread an interesting module which I found recently on CPAN, Acme::Comment - This source filter module allows for comments of many different styles to be incorporated into your code, including multi-line C++ style comments. For example:

use Acme::Comment type => 'C++';

/*
    This is a comment ... 

    ... C++ style!
*/
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Other commenting styles available through this module include - Fortran, HTML, LaTeX, Lisp and Pascal.

The problem with just using a here document is that it will issue a warning under '-w'. It's much better to use the little known << >> operator.

    <<q=~q>>;
      This is a multiline comment.
    q
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Here's another style, that uses the C preprocessor:

#! /usr/bin/env perl -P

#if 0
this is a
multi-line
comment
#endif
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q^
In case you
were wondering,
this is a multi-line
comment.
^ if 0;
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A "not-really-comment" that may be used also as a usage message...

my $comment= <<END_COMMENT
this is how my script works
and this is why it doesn't work
blah blah
END_COMMENT
; # don't forget the final ";"
[download]

There's a variety of ways to add comments using POD.

Quick and dirty method to comment out some code:

=pod

    ... lines to comment out ...
    ... should be indented ...

=cut
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Adding a single line comment:

=for comment Some single comment line

=cut

...

=for comment
Some single comment line

=cut
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Adding a multiline comment:

=for comment Some comment
with multiple
lines.

=cut

...

=for comment
Some comment
with multiple 
lines.

=cut
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Adding a multiblock coment:

=for comment

lines from
first block

lines from
next block

...

lines from
last block

=cut
[download]

Was having a bit of concern due to multi-line comment feature not readily available in perl.

Started to look-out for options and came across this post, and subsequently came to know the various ways we implement the multi-line comment.

Just took one of the options and slightly modified it and have been using it in way like a "defacto" standard in my scripts.

It was nice when i started to use it, and thought would share it.

--- multi-line comment syntax ---

q##//q#
   ... comments ...
   ... comments ...
#;
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--- example ---

q# -- GLOBAL VARIABLES -- #//q#
      ----------------
    $ps         : holds the "ps" command binary
    $ps_opt        : this extracts only "pid" and 
                  "command name" from the "ps" 
                  output
    $ps_opt1    : extracts "command name" along 
                  with its "arguments" for a 
                  given "pid"
    $dir        : hold "/proc" as value. 
                  This is the source directory 
                  from where the search for 
                  required informations for each 
                  pid starts
    $total_swap    : stores the sum of swap usage of 
                  all the individual threads/processes
    @proc_swap    : this array holds the "ref_arrays"
                  in each of its index
    $PROC        : is the file/command handle which
                  holds the information of all the
                  contents within "/proc" directory
#;
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-------------------

Thanks

Other applicable form :

q# comment_heading # //
q#
  ... comment ...
  ... comment ...
#;
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"comment heading" -> is optional
space between "#" and "//" -> is optional

one more way :

' comment heading ' //
'
  ... comment ...
  ... comment ...
';
[download]

This will be bit more standardized as we might feel like using other characters instead of "#" along with "q" as shown above.
Single quote (') will help in maintaining uniformity while implementing multi-line comments.

a very simple way :

''//'
  ... comments ...
  ... comments ...
';
[download]