Linux is open source, which means anyone can see, modify, and distribute its code

Open source means the source code — the human-readable instructions that make the software work — is publicly available. With Linux, you can read the code, read it, change it, and share your changes. You don't need permission from a company. This is different from Windows or macOS, where the code stays locked away and only the company that owns it can modify the core system.

Linux started in 1991 when Linus Torvalds wrote the kernel (the core part that manages your hardware) and released it under an open source license. Other programmers around the world added tools, drivers, and features. Today, thousands of people contribute to Linux — some paid by companies like Red Hat or Canonical, others volunteering.

Being open source doesn't mean Linux is free of charge, though most versions are. It means the source code is transparent. Anyone can audit it for security holes. Anyone can fix bugs. Anyone can build a version tailored to their needs — from smartphones to supercomputers to your home router.

Key Takeaways

  • Linux's source code is publicly available and can be modified by anyone, unlike proprietary operating systems where only the company controls changes.
  • Open source licenses like the GPL require that if you distribute modified Linux code, you must share your changes under the same license.
  • You can use Linux without paying anything, but companies like Red Hat and Canonical sell support, services, and certified versions.
  • The transparency of open source code means security vulnerabilities are often found and fixed faster than in closed systems.

How open source licenses control what you can do with Linux

Open source doesn't mean "do whatever you want." It means the code is governed by a license that sets rules. Most Linux distributions use the GNU General Public License (GPL), which says: you can use, modify, and share Linux, but if you distribute a modified version, you must release your changes under the same GPL license.

This is called copyleft. It prevents someone from taking Linux, adding proprietary code on top, and selling it as closed-source software. If you modify Linux and sell it, your customers have the same rights you did — they can see the code and modify it themselves.

Other open source licenses have different rules. The MIT License and Apache License are more permissive — you can modify the code and keep your changes private. But GPL is the dominant license for Linux itself, which is why Linux remains open and free to modify.

Why companies use and contribute to open source Linux

You might wonder: if Linux is free and open, how do companies make money? Red Hat, Canonical, and others don't sell the software itself. They sell support — they may provide that their version of Linux will work on your servers, they provide security updates, and they send engineers to fix problems when things break.

Companies also contribute to Linux because they use it. Google, Amazon, Meta, and Microsoft all run Linux on millions of servers. When they find a bug or need a feature, they fix it and contribute the code back. This benefits everyone — the bug stays fixed in the official version, and they don't have to maintain a separate fork.

Hardware makers like Intel and Nvidia contribute drivers so their products work well with Linux. Phone makers use Linux in Android. The open source model means these companies can shape the software they depend on without paying licensing fees to a single owner.

The difference between open source and free software

"Open source" and "free software" are related but not identical. Free software emphasizes freedom — the freedom to run, modify, and share code. Open source emphasizes the practical benefits: transparency, security, and faster development. Most Linux distributions are both open source and free software, but the terms describe different values.

Linux itself is free to read and use. Most distributions (Ubuntu, Fedora, Debian) are also free. But "free" here means freedom and zero cost. Some companies sell support contracts or certified versions, and that's allowed under the GPL — you're paying for service, not for the software itself.

How open source affects security and updates

Because Linux code is public, anyone can read it and find vulnerabilities. This sounds risky, but in practice it's an advantage. Thousands of security researchers and developers review the code constantly. When a hole is found, it's usually patched within days. With closed-source systems, you rely on the company to find and fix problems, and you might not know a vulnerability exists until it's exploited.

Linux updates are released regularly and publicly. You can see exactly what changed, why it changed, and who made the change. If a security patch breaks something, the community usually knows quickly and a fix appears soon. With proprietary systems, you get updates on the company's schedule, and you have to trust that the company tested them thoroughly.

The transparency also means you can verify that Linux doesn't contain hidden tracking, spyware, or backdoors. You can't do that with Windows or macOS — you have to trust Microsoft or Apple.

What "open source" means for your choices as a user

If you use Linux, you benefit from open source even if you never touch the code. Your system gets security updates faster. You can switch between distributions (Ubuntu, Fedora, Debian) without losing your data or paying switching costs — they all use the same open source kernel. If a company stops supporting a version you use, the community can keep it alive.

You also have choices about what software runs on your system. Most Linux software is also open source, so you're not locked into one vendor's ecosystem. You can replace components, customize the interface, or strip out features you don't need.

The downside is that open source software sometimes has fewer polished features or less user-friendly interfaces than proprietary alternatives. Documentation can be scattered. Support depends on the community or a paid vendor, not a single company with a phone number. But the transparency and freedom are real advantages if you value control over convenience.

Frequently Asked Questions

Does open source mean Linux has no security?

No. Open source means the code is visible, which actually makes security easier to verify. Vulnerabilities are found and fixed by thousands of developers worldwide. Closed-source systems can hide vulnerabilities for years without anyone knowing.

Can I use Linux commercially if it's open source?

Yes. The GPL allows commercial use. You can run Linux on servers, sell services built on Linux, or sell devices that run Linux. You just can't take Linux, modify it, and sell it as proprietary software without sharing your changes.

If Linux is free, why do companies like Red Hat charge for it?

They don't charge for the software itself — you can read it free. They charge for support, security updates, training, and certified versions that work on specific hardware. You're paying for service, not the code.

Can I modify Linux and keep my changes private?

You can modify Linux for your own use without sharing changes. But if you distribute your modified version to others, the GPL requires you to share the source code under the same license.

Is Android open source like Linux?

Android is built on the Linux kernel and is mostly open source, but Google controls the core components and the app store. You have more freedom than with iOS, but less than with a desktop Linux distribution.