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Can someone clarify these claims:
This module is free software you can redistribute it and/or modify it under the same terms as Perl itself. Copyright (C) year Some Author. All Rights Reserved
It looks like terms are the opposite.
This is the customary license for Perl modules.
“All rights reserved” is just a reminder that someone holds the copyright for this code. By default, only the copyright holder may distribute copies of the program, or publish modified versions of the code. This is the “default license” for any code you see on the internet. You can't really do anything with it unless you get explicit permission.
However, the copyright holder has given you a license: “you can redistribute and/or modify it under the same terms as Perl itself”. This is a rather vague statement, but currently the Perl license is:
Perl is free software; you can redistribute it and/or modify it under the terms of either:
a) the GNU General Public License as published by the Free Software Foundation; either version 1, or (at your option) any later version, or
b) the "Artistic License" which comes with this Kit.
The Perl documentation contains a copy of the GPLv1 and Artistic License. Larry Wall, the original author of Perl, has given a non-standard interpretation of the GPL which makes Perl's usage of the GPL effectively very similar to the LGPL license.
You are free to use the module under the license terms of either the GPLv1 (or later) or the Artistic License. The Artistic license gives you substantial flexibility to use the module even for commercial purposes, but has a number of unusual restrictions that apply when you modify the module.
“Free software” doesn't mean you are free to do anything you want. However, free software culture tries to ensure as much freedom as possible for users, in contrast to proprietary software where EULAs try to give you as few freedoms as possible. The Free Software Foundation has published a Free Software Definition:
“Free software” means software that respects users' freedom and community. Roughly, it means that the users have the freedom to run, copy, distribute, study, change and improve the software. Thus, “free software” is a matter of liberty, not price. To understand the concept, you should think of “free” as in “free speech,” not as in “free beer”. […]
A program is free software if the program's users have the four essential freedoms:
The freedom to run the program as you wish, for any purpose (freedom 0).
The freedom to study how the program works, and change it so it does your computing as you wish (freedom 1). Access to the source code is a precondition for this.
The freedom to redistribute copies so you can help your neighbor (freedom 2).
The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.
By calling the module “free software”, the module author signals their intention to respect these freedoms. However, the term has no legal significance. The legally relevant part is the content of the license text, as discussed above.
