// Software should be free. Here's why.
PROPRIETARY SOFTWARE IS A TRAP.
Every proprietary program you use is a cage. You're not allowed to see how it works, modify it to your needs, or share it with others. You're dependent on the vendor's goodwill, their pricing, their support, their future decisions. If they raise prices, change features, or go out of business, you're stuck.
FREE AS IN FREEDOM.
Free and Open Source Software (FOSS) is software that respects your freedom. You can run it, study it, modify it, and share it. This isn't about being cheap—it's about autonomy. It's about control over the tools you use every day.
THE WORLD OWES YOU NOTHING—BUT YOU CAN STILL CHANGE IT.
By using, developing, and advocating for free software, you're participating in a movement that's shaping the future of computing. You're standing with thousands of developers who believe software should serve users, not corporations.
12 lessons. Complete FOSS understanding.
Free vs open source. The four freedoms. FOSS history.
BeginnerRichard Stallman, GNU, FSF. The origins of free software.
BeginnerTwo philosophies. Where they overlap. Where they differ.
BeginnerGPL, MIT, Apache, Creative Commons. Understanding licenses.
BeginnerShare-alike. Weak vs strong copyleft. Why it matters.
IntermediateGPLv2, GPLv3, LGPL, AGPL. Which to use when.
IntermediateMIT, BSD, Apache. Using permissive FOSS.
IntermediateHow to contribute. Finding projects. Pull requests.
IntermediateLicensing from day one. Community building. Maintenance.
AdvancedUsing FOSS commercially. Compliance. Dual licensing.
AdvancedReplacing proprietary software. The FOSS ecosystem.
AdvancedSustainability. Corporate involvement. The road ahead.
AdvancedAccording to the Free Software Foundation, free software means programs that respect users' freedom. Specifically, there are four essential freedoms:
The Open Source Initiative defines open source through ten criteria:
In 1983, Richard Stallman announced the GNU Project—the first major effort to create a complete free operating system. He founded the Free Software Foundation (FSF) in 1985 to promote free software.
Stallman created the GNU GPL, emacs, GCC, GDB—foundational tools that form the backbone of much of today's software.
GNU (GNU's Not Unix) aimed to create a complete UNIX-like operating system—all free software. By the early 1990s, GNU had most components ready: compilers, editors, shells, core utilities.
What was missing: the kernel. Linux, created by Linus Torvalds in 1991, filled that gap. Together, GNU + Linux created the GNU/Linux operating system most people just call "Linux."
The Free Software Foundation (fsf.org) works to preserve, protect, and promote free software:
Despite often being used interchangeably, "free software" and "open source" represent different philosophies:
Both movements support:
For most practical purposes—using, contributing to, or releasing FOSS—the differences are subtle. Both movements have produced incredible software.
| Goal | Recommended License |
|---|---|
| Maximum copyleft | GPLv3 |
| Library use | LGPL |
| Permissive, simple | MIT |
| Permissive, with patents | Apache 2.0 |
| No restrictions | CC0 / Unlicense |
Copyleft is a legal concept that requires derivative works to also be free. It's like copyright, but inverted—you must share alike.
Can link with proprietary software, but changes to the library itself must be shared.
Any work that links to or modifies the software must be released as GPL.
The original GNU GPL, used by Linux kernel and thousands of projects. Key requirement: if you distribute binaries, you must make source available.
Updated version addressing:
Closes the "ASP loophole"—if you use the software as a service (SaaS), you must still share source code with users.
Simple, permissive, one of the most popular licenses. Only requires preservation of copyright and license notice.
Similar to MIT but includes a clause preventing endorsement from the author's name.
Similar to MIT but includes explicit patent grants from contributors. Good for projects where patents are a concern.
Choose a license before publishing. Without a license, default copyright applies—no one can use your code.
FOSS offers significant advantages:
Some projects offer dual licensing—GPL for open source users, commercial license for proprietary use. MySQL and MongoDB use this model.
| Proprietary | FOSS Alternative |
|---|---|
| Microsoft Office | LibreOffice, OnlyOffice |
| Google Docs | Nextcloud Office |
| Slack | Matrix/Riot, Mattermost |
| Dropbox | Nextcloud, Syncthing |
| Proprietary | FOSS Alternative |
|---|---|
| GitHub | Gitea, GitLab |
| Docker Hub | Harbor, GitHub Packages |
| Jenkins | GitLab CI, Drone |
You've completed the FOSS Mastery guide. You now understand:
Remember: