It is a way of using data that is directly placed inside of the script within the __DATA__ section of the file.

It works like a filehandle but does not need to be opened or closed.

For example,

use strict;
use warnings;

while (<DATA>) {

  # works just like a file
  my $line = $_;

  # removes line feed
  chomp($line);

  # ..... add your code here

  print "LINE: $line\n";

}

__DATA__
Line 1
Line 2
Line 3
Line 4
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