Source files of,,,,, and Contribute:
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

616 lines
26 KiB

<?xml version="1.0" encoding="UTF-8" ?>
<title>Legal FAQs</title>
<p id="category"><a href="/freesoftware/legal/legal.html">Legal issues in Free Software</a></p>
<h1>Frequently Asked Questions on Free Software Licensing</h1>
<div id="introduction">
This page aims to cover the most frequently asked questions about
Free Software (also known as Open Source), copyright, and licensing. For more in depth information about REUSE, please also look at the <a
href="">FAQ page of our REUSE project</a>. If you need more in depth general information about Free Software licensing, please also refer to our general <a href="">Free Software legal documentation</a>, prepared for the <a href="/activities/ngi">Next Generation Internet Zero initiative</a>.
If your question is not covered here or in any of our other resources, you can consider asking our <a
Questions team</a>.
<h2>The Basics</h2>
<li><a href="#freesoftware">What is Free Software?</a></li>
<li><a href="#opensource">What is Open Source Software?</a></li>
<li><a href="#proprietary">What is proprietary software?</a></li>
<li><a href="#commercial">How can Free Software be used commercially?</a></li>
<li><a href="#copyright">What is Copyright?</a></li>
<li><a href="#copy">Can I copy someone else’s work?</a></li>
<li><a href="#no-license">Can I copy a work that has no copyright notice or license?</a></li>
<li><a href="#copyrightable">Which files are copyrightable?</a></li>
<li><a href="#author">What is a copyright holder, and what is an author?</a></li>
<li><a href="#public-domain">What is public domain?</a></li>
<li><a href="#license">What is a license?</a></li>
<li><a href="#software-license">What is a software license?</a></li>
<li><a href="#license-types">Are there different types of software licenses?</a></li>
<li><a href="#copyleft">What is copyleft?</a></li>
<li><a href="#own-license">Can I write my own Free Software license for my work?</a></li>
<li><a href="#choose-license">What should I consider when choosing a license?</a></li>
<h2>License Compatibility</h2>
<li><a href="#compatibility">What does it mean to say that licenses are compatible?</a></li>
<li><a href="#use-proprietary">Can code covered by Free Software licenses be used in proprietary software?</a></li>
<li><a href="#permissive">What are permissive licenses?</a></li>
<li><a href="#fs-compatibility">Are all Free Software licenses compatible with each other?</a></li>
<li><a href="#permissive-compatible">What kind of licenses are compatible with permissive licenses?</a></li>
<li><a href="#copyleft-compatible">Can copyleft licenses be compatible with other Free Software licenses?</a></li>
<h2>Free Software</h2>
<h3 id="freesoftware">What is Free Software</h3>
The FSFE maintains an easy understandable <a
href="/freesoftware/freesoftware.html">overview page about what Free Software
is</a> in several languages, providing more information about the four
freedoms and their meaning, the fundamentals about Free Software licenses,
the advantages that Free Software provides, and the most common synonyms.
The term “Free Software” is a regulated term created by the <a href="">Free
Software Foundation</a>. It refers to software that enables its users to
maintain their control and freedom over how to use such software.
More specifically, Free Software is defined by users being able to
enjoy the four essential freedoms: the freedoms to use, to study, to
share, and to improve the software.
<h4>Freedom to Use</h4>
Installing and running the program is not restricted. Placing
restrictions on the use of Free Software, such as time ("30 days
trial period", "license expires January 1st, 2004"), purpose
("permission granted for research and non-commercial use", "may not
be used for benchmarking"), or geographic area ("must not be used in
country X") makes a program non-free.
<h4>Freedom to Study</h4>
Placing legal or practical restrictions on the comprehension or
modification of a program, such as mandatory purchase of special
licenses, signing of a Non-Disclosure-Agreement (NDA) or - for
programming languages that have multiple forms or representation -
making the preferred human way of comprehending and editing a program
("source code") inaccessible also makes it proprietary (non-free).
Without the freedom to modify a program, people will remain at the
mercy of a single vendor.
<h4>Freedom to Share</h4>
Software can be copied/distributed at virtually no cost (i.e. license
fees and royalties are not permitted). If you are not allowed to give
a program to a person in need, that makes a program non-free. This
can be done for a charge, if you so choose.
<h4>Freedom to Improve</h4>
Not everyone is an equally good programmer in all fields. Some people
don't know how to program at all. This freedom allows those who do
not have the time or skills to solve a problem to indirectly access
the freedom to modify. This can be done for a charge.
These freedoms are rights, not obligations, although respecting those
freedoms for society may at times oblige the individual. Any person
can choose to not make use of them but may also choose to make use of
all of them.
Free Software does not exclude commercial use. If a program fails to
allow commercial use and commercial distribution, it is not Free
Software. A growing number of companies base their business model
completely, or at least partially on Free Software, including some of
the largest proprietary software vendors. Free Software makes it
legal to provide help and assistance; it does not make it mandatory
to do so.
Free Software is therefore a matter of liberty, not of price; the
word “free” in Free Software means “free” as in “free speech”, not as
in “free beer”.
<h3 id="opensource">What is Open Source software?</h3>
You might have also come across the term “Open Source” software, which was created as
a synonym for Free Software in 1998. The term also
describes the complete set and range of software licenses that give
users the right to use, study, share, and improve the software. The
term “Open Source” is regulated by the Open Source Initiative (the OSI), which
states that “Open Source” (Free Software) doesn't just mean access to the source code,
but must comply with the
<a href="">following criteria</a>:
<li>Free Redistribution: The license shall not require a royalty or
other fee for the distribution by the licensee.</li>
<li>Source Code must be included</li>
<li>Derived Works must be permitted</li>
<li>Integrity of The Author's Source Code: The license may require
derived works to carry a different name or version number from the
original software</li>
<li>No Discrimination Against Persons or Groups</li>
<li>No Discrimination Against Fields of Endeavor</li>
<li>Distribution of License: The rights attached to the program must
apply to all to whom the program is redistributed without the need
for execution of an additional license by those parties.</li>
<li>License Must Not Be Specific to a Product</li>
<li>License Must Not Restrict Other Software</li>
<li>License Must Be Technology-Neutral</li>
You can refer to a <a
href="">list of OSI approved Free Software
licenses here</a>.
<h3 id="proprietary">What is proprietary software?</h3>
Proprietary software is the opposite of Free Software. This term is
used to refer to software that is distributed under restrictions that
prevent users from enjoying the <a href="#freesoftware">four
essential freedoms</a>. Even software that is distributed gratis can
be considered proprietary, if its restricts users from any of the
four essential freedoms.
The term “commercial software” is sometimes used carelessly to refer
to proprietary software. This would be incorrect: as explained below,
Free Software does not exclude commercial use.
<h3 id="commercial">How can Free Software be used commercially?</h3>
Free Software can be sold, as long as the buyers are not restricted
from sharing copies of the software after their purchase. Hence,
requiring a fee for any copy distributed by the user is not
permitted. Free Software can also be commercialized in other ways,
such as by selling support, services, and certification. Free
Software remains free as long as the <a href="#freesoftware">four
essential freedoms</a> outlined above are afforded to users.
<h3 id="copyright">What is copyright?</h3>
Copyright is a legal construct that grants someone exclusive rights
over a creative work. The most important exclusive right is in the
name: the right to produce copies. Only the copyright holder is
allowed to reproduce a work and to give new copies of their work to
third parties. Additionally, the copyright holder has the exclusive
right to modify the work and to make it publicly available (e.g.
offering it up for download).
Usually, the author is the copyright owner, but copyright is often
transferred to the author’s employer, in many cases automatically.
This is often stated in an employee’s employment contract.
You do not need to do anything to gain copyright. As soon as you make
a creative work, you (or your employer) inherently possess the
copyright over it.
<h3 id="copy">Can I copy someone else’s work?</h3>
If someone else has made their work available for you under a Free
Software license, you can incorporate their work into your project.
When you put the work in one of the files in your project, you should
add an <em>SPDX-FileCopyrightText</em> tag for the copyright
holder(s) and an <em>SPDX-License-Identifier</em> tag for the
license(s) under which the work was made available. You can learn
more about how to do this with our <a
href="">REUSE initiative</a>.
<h3 id="no-license">Can I copy a work that has no copyright notice or license?</h3>
Before you proceed, always first make sure that you can find the
copyright and licensing information elsewhere. Some projects only
include this information in the root directory or in their README
If the work has no license, that means that you do not have the right
to copy it, or it is in the <a href="#public-domain">public
domain</a>. If you believe that this is a mistake and the author
clearly meant for you to be able to copy this work, you should
contact the author and ask them to license their work. Feel free to
refer them to our <a href="">REUSE
initiative</a> on the best practices to do this.
<h3 id="copyrightable">Which files are copyrightable?</h3>
All files that are original works of authorship are copyrightable. In
essence. If someone sat down typing their own original thoughts on a
keyboard, then that person holds copyright over the output. Common
examples are source code, documentation, audio, and video.
However, there are some edge cases. For example, the program
<p><i>print("Hello, user!")</i></p>
probably does not meet the threshold of originality because it is too
trivial. Similarly, data files and configuration files may not meet
that threshold either.
<h3 id="author">What is a copyright holder, and what is an author?</h3>
In these resources, we maintain a distinction between the copyright
holder and the author. The author (also known as creator) is the
person who sat down and created a work. Think of the author as a
programmer, writer, or artist.
The copyright holder is the person who has the exclusive rights over
that work. Often the author and the copyright holder are the same.
However, if the author is being paid by their employer to create a
work, the employer is the copyright holder.
Keep in mind that in some jurisdictions, the word "author" is often
used as a synonym for "copyright holder". In other jurisdictions,
authors maintain some rights over their work even if they are not the
copyright holder.
<h3 id="public-domain">What is public domain?</h3>
The public domain consists of all the creative work (including
software) to which no copyright applies. The rights to these works
may have expired, been expressly waived, or may be inapplicable.
While these are the very general principles behind the public domain, the decisive factor of what constitutes public domain will always be determined by the legal principles in the country in which a work is to be used. This is because different national jurisdictions often differ in how they apply fundamental elements of copyright, which can have the effect of impacting what constitutes the public domain in that country. For example, in Germany, authors cannot voluntarily waive all copyright claims and completely mark their own works as belonging in the public domain. While the economic rights of use can be granted to the general public, the copyright cannot be relinquished completely in Germany. This is in contrast with interpretations of copyright law in the United States, for example, where a work may be freely usable and exploitable due to its “public domain” classification.
While software in the public domain certainly can overlap with the aims of Free Software, as a rule, Free Software is not synonymous with public domain. Indeed, most of Free Software is bound by the rules of copyright. Especially in the European Union, the existing copyright and patent systems make it difficult to identify a work under the public domain accurately.
To avoid ambiguities in how you intend to share a piece of work, it therefore is preferable to use a Free Software license rather than to placing the work in the public domain, as a Free Software license is able to provide clear and comprehensible legal information on the rights and obligations over that software. If you wish to place your work as close as possible into the public domain, the <a href="">Creative Commons CC0 1.0 Universal (CC0) License</a> can be used to waive copyright to the extent you may have these rights in your work.
Please note that the <a href="#no-license">absence of a license</a>
does not make a software free to use. Software is copyrighted by
default, so unless it has been explicitly and validly placed in the
public domain, using code without a license may be considered
copyright infringement.
<h3 id="license">What is a license?</h3>
One problem with copyright (as it relates to software) is that it
makes software unshareable by default. A license changes that. A
license defines the terms under which the copyright holder allows the
recipient of the license to use (i.e. to run, copy, distribute and/or
modify) the software. If the license allows the recipient to use,
study, share, and improve the software, then that software is Free
<h3 id="software-license">What is a software license?</h3>
Generally, a license is an authorization to use, release, or
distribute someone else’s property. This includes intellectual
property such as a piece of text, a song, or software.
Software licenses tell people how the rights holder (usually the
author of the software) wants the software to be used and what
freedoms, or restrictions, the software has. Without a license, any
use of the software is prohibited by default except in the case of a
statutory exception to copyright.
Please note that the absence of a license does not make a software
free to use. Software is copyrighted by default, so unless it has
been explicitly and validly placed in the <a
href="#public-domain">public domain</a>, using code without a license
may be considered copyright infringement.
<h3 id="license-types">Are there different types of software licenses?</h3>
Yes. Software licenses can be classified according to the rights
granted or retained by the copyright owner. When the owner of a
software waives all of these rights, the software is in the Public
Domain. Please note that a complete waiver of copyright may not work
in all jurisdictions. For such cases, use of the <a
href="#public-domain">CC0 License</a> achieves this goal practically.
If a software is under a proprietary license, only a few rights are
granted; for example, the right to use program but not to distribute
copies of it. If the license grants the four essential freedoms to
use, study, share, and improve the software, it is a Free Software
license. You can find here lists of Free Software licenses <a
href="">evaluated by the Free Software Foundation</a> and <a
href="">approved Free Software licenses by the Open Source Initiative</a>.
For other license categories, <a
is a list prepared by IfrOSS</a>.
<h3 id="copyleft">What is copyleft?</h3>
Copyleft is a form of Free Software licensing that gives permission
for a user to enjoy the four freedoms of Free Software, under the
condition that those freedoms remain intact in further distribution
of the software or derivative works. That’s why copyleft licenses are
also called “reciprocal licenses”. This is in contrast to “permissive
or non-reciprocal” licenses, which, unlike copyleft licenses, allow
the creation of derivative versions of the software with different
license terms from the original, which can in some cases result in a
derivative work being placed under a proprietary license.
In practical terms, having a copyleft license would generally mean
that the derivative and/or combined work has to be licensed under the
same license as the original work. As a result, this ensures that a
copylefted piece of Free Software can remain free, and cannot be
transformed into proprietary software.
An example of a copyleft license is the <a
href="">GNU General Public
License</a>. Under this license, derivative works can only be
distributed under the same license terms. This is distinct from
permissive (non-reciprocal) licenses, which include the commonly used
<a href="">MIT License</a> and <a
href="">Apache License
<h3 id="own-license">Can I write my own Free Software license for my work?</h3>
Anyone can write their own Free Software license to dictate the terms
and conditions of use of their work. However, we strongly recommend
you to use an existing well-known license, instead of making up your
Licenses should be written to apply in complex legal issues, and
people are more likely to use works under established and existing
licenses whose legal effects are well known and have been clearly
documented. The legal effects of a new license would be ambiguous,
and this would have the effect of discouraging users from adopting
your software.
Another reason to not write your own license is to prevent license
proliferation. There are already numerous licenses available with
very similar terms, which are often incompatible with each other. The
standardization of license terms can make things easier for everyone.
Conversely, inventing a new license would make it harder for the
community to keep track of all available licenses and would be a
hindrance to developers who simply want to combine code under
different licenses.
<h3 id="choose-license">What should I consider when choosing a license?</h3>
Having a Free Software license is the best way to protect your
project’s contributors and users. A license can determine the way
people contribute to the project and how the software will be used
and shared.
If you are taking part in a project that has already determined which
licenses to use, the best way to contribute is to continue using that
project’s license. Some <a
href="">communities</a> have
strong preferences for particular licenses. If you want to
participate in one of these communities, it will be easier to use the
preferred license even if you’re starting a brand new project with no
existing dependencies. However, if you don’t see your project as part
of a community, you have more flexibility with which Free Software license to
There are two objectives to pursue with a Free Software license:
Make the code as simple and permissive as possible. If you plan to
let people and organisations to use your code in the most simple
way, lax permissive licenses let people do almost anything they want
with your project, including to make and distribute closed source
Protecting the code’s freedom. Copyleft protects software freedom,
permitting people to do almost anything they want with your
project, except to distribute proprietary versions.
<h2>License Compatibility</h2>
<h3 id="compatibility">What does it mean to say that licenses are compatible?</h3>
When your project combines two pieces of Free Software into one, or
merges code from one into another, it is important to pay attention
to whether the licenses of each software or code allow this
combination, or prohibit it. If the licenses allow it, the licenses
can be said to be “compatible” with one another.
If they prohibit it, the licenses can be said to be “incompatible”
with one another. In other words, we say that several licenses are
compatible with each other if if it possible to combine code under
these different licenses, while still complying with the terms and
conditions of all of these licenses. It is therefore important that,
when you incorporate existing code from a third party, you ensure
that the license of that third party code is compatible with the
license that you intend to issue your software project under.
Being compatible also means that code under one Free Software license
can be combined with code under another, and the resulting software
can be distributed under either Free Software license without
violating the terms of the other.
Using incompatible licenses may result in copyright infringement.
<h3 id="use-proprietary">Can code covered by Free Software licenses be used in proprietary software?</h3>
Generally, Free Software licenses allow anyone to modify the code
covered, and to redistribute it in both its original and modified
form. In principle, this could result in redistribution of the code
and its derivative works under a proprietary license.
<h3 id="permissive">What are permissive licenses?</h3>
Permissive Free Software licenses (also known as non-copyleft
licenses) allow their code to be used in proprietary derivative
works. In such a case, the derivative work will still be proprietary,
not withstanding that it contains code from a source that is covered
by a Free Software license. Examples of permissive licenses that
allow covered code to be used in proprietary derivative works include
the Apache license, the MIT license, and BSD licenses.
Conversely, copyleft licenses like the GNU General Public Licenses (GPL) require that any derivative work must be distributed under the same terms, and be Free Software as well.
<h3 id="fs-compatibility">Are all Free Software licenses compativle with each other?</h3>
No. While all of the commonly-used permissive Free Software licenses
are compatible with each other, copyleft licenses (that do not allow
their covered code to be used in proprietary software) can and are
prone to creating license incompatibilities, depending on each unique
situation and the licenses involved.
<h3 id="permissive-compatible">What kind of licenses are compatible with permissive licenses?</h3>
Probably all permissive licenses are compatible with each other, as
they do not contain inconsistent provisions. Different license
conditions must be met cumulatively.
<h3 id="copyleft-compatible">What kind of licenses are compatible with permissive licenses?</h3>
Because copyleft licenses provide that derivative works may only be
used under the same license conditions, copyleft licenses are only
compatible with other Free Software licenses when one of the following
conditions is met:
The other Free Software license does not contain any license
requirements that are not provided by the compatible copyleft
license. This is the case with the BSD license without an
advertising clause, whereas the BSD license with an advertising
clause contains an information requirement that the GPL and other
copyleft licenses do not provide.
The other Free Software license contains a special compatibility or
opening clause. This is the case for example in sec. 3 of the LGPL
Version 2.1, that permits the use of LGPL code under the GPL. GPLv3
contains a compatibility clause for the Affero GPL and opening
clauses for Apache license 2.0 and other licenses. The European
Public License (EUPL) and German free software license (d-fsl)
contain compatibility clauses for the GPL.