GNU Free Documentation License 1.3 (GFDL 1.3)

Overview

The GNU Free Documentation License (GFDL) is a copyleft license published by the Free Software Foundation, specifically designed for documentation, manuals, and other textual works.

Version: 1.3, November 3, 2008
Official URL: https://www.gnu.org/licenses/fdl-1.3.html

Core Philosophy

The purpose of GFDL is to make documents "free" in the sense of freedom: to assure everyone the effective freedom to copy and redistribute them, with or without modifications, either commercially or noncommercially.

What You Can Do

✅ Verbatim Copying

Copy and distribute the document in any medium
For commercial or noncommercial purposes
Must preserve license, copyright notices, and license notice

✅ Modifications

Create and distribute modified versions
Add, remove, or change content
Translate into other languages
Requirement: Modified versions must also use GFDL license

✅ Combining Documents

Combine multiple GFDL documents into one
Preserve all Invariant Sections

Key Requirements

📝 What Must Be Preserved

Copyright Notices - All original copyright information
License Text - Complete GFDL license
Invariant Sections - If any exist, must remain unchanged
Cover Texts - Front-Cover Text (max 5 words) and Back-Cover Text (max 25 words)

🔄 Modified Version Requirements

When creating modified versions, you must:

Use a title distinct from the original document
List authors of modifications on the title page
Add appropriate copyright notice for modifications
Preserve "History" section and add modification record
Preserve all Invariant Sections
Remove any "Endorsements" sections

🚫 Restrictions

Cannot alter Invariant Sections - These must remain as-is
Cannot remove copyright information - All copyright notices must be preserved
Modified versions must use GFDL - Cannot use other licenses

Special Concepts

📋 Invariant Sections

Special sections designated by the original author
Content cannot be modified, but formatting can be changed
Typically include acknowledgments, history, etc.

📖 Transparent Format

Documents should be provided in transparent formats, including:

Plain ASCII text
Texinfo input format
LaTeX input format
SGML or XML using publicly available DTD
Standard HTML, PostScript, or PDF

🔒 Opaque Format

Includes proprietary formats such as:

Formats readable only by proprietary word processors
Machine-generated HTML, PostScript, or PDF

Use Cases

✅ Content Suitable for GFDL

Technical Documentation - Software manuals, API documentation
Educational Materials - Tutorials, guides
Reference Materials - Dictionaries, encyclopedia entries
Open Source Project Documentation - README files, user guides

⚠️ Scenarios Requiring Consideration

Wikipedia-style Collaboration - CC BY-SA might be more suitable
Commercial Documentation - Not suitable if you don't want competitors to use it
Simple Blog Posts - Might be overly complex

License Compatibility

🔄 CC BY-SA Compatibility

GFDL 1.3 added one-way compatibility with Creative Commons Attribution-ShareAlike 3.0:

Qualifying GFDL content can be relicensed as CC BY-SA
But CC BY-SA content cannot be relicensed as GFDL

🚫 Incompatible Licenses

Proprietary licenses
Most other open source licenses (unless explicitly compatible)

Termination

If you violate the license terms:

Your rights automatically terminate
Rights may be restored if violation ceases within 60 days
Rights permanently restored if violation is cured within 30 days

Practical Usage Guidelines

📝 How to Apply GFDL

Include the following notice in your document:

Copyright (C) YEAR YOUR NAME
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
A copy of the license is included in the section entitled "GNU
Free Documentation License".

⚠️ Important Considerations

Carefully consider Invariant Sections - Once designated, they cannot be changed
Keep documentation updated - Ensure license information is correct
Provide transparent formats - Facilitate modification by others

Frequently Asked Questions

Q: What's the difference between GFDL and GPL? A: GPL is for software code, GFDL is for documentation. Both are copyleft licenses but apply to different types of works.

Q: Can GFDL documents be used commercially? A: Yes, GFDL allows commercial use, but requires maintaining the same license.

Q: If I only want to quote a few sentences, do I need to follow GFDL? A: Short quotations typically fall under fair use and don't require GFDL compliance. However, substantial copying does require license compliance.

Legal Notice

This document is a simplified explanation of GFDL 1.3 and has no legal force. Please read the complete license text carefully before use.

The Free Software Foundation is not a law firm and does not provide legal services. Distributing, displaying, or linking to this summary does not create a lawyer-client relationship.