Linux Turns 25: Celebrating the Open Source OS That Changed Everything

25 years ago, a momentous event quietly took place that would change the world of computing forever. On August 25, 1991, a 21-year-old university student in Helsinki, Finland made an announcement on the comp.os.minix newsgroup:

"I‘m doing a (free) operating system (just a hobby, won‘t be big and professional like gnu) for 386(486) AT clones."

That student was Linus Torvalds, and the "hobby" operating system he spoke of would come to be known as Linux. Little did anyone realize at the time just how profoundly this modest newsgroup post would shake up the software world.

Today, Linux is everywhere. The open-source operating system powers everything from Android phones to laptops, servers, supercomputers, embedded systems, and more. To commemorate the 25th anniversary of Linux, let‘s take a look at 25 interesting facts about this groundbreaking OS and how it grew from a small hobby project into a global phenomenon.

1. Linux began as a personal project by Linus Torvalds.

As a computer science student at the University of Helsinki in 1991, Torvalds wanted to create a free operating system kernel as a fun programming challenge. He had been using Minix, a simplified educational version of Unix, but was frustrated by its limitations. Torvalds decided to develop his own kernel from scratch.

2. "Linux" is actually the name of the kernel, not the entire OS.

Strictly speaking, Linux refers to the core kernel that Linus Torvalds developed. The kernel handles key functions like memory management, multitasking, and device drivers. The rest of what we think of as a complete Linux operating system includes additional programs, many from the GNU project (more on that later). This is why some argue the OS should properly be called "GNU/Linux."

3. Linux was inspired by Unix but doesn‘t contain any Unix code.

Unix, developed by AT&T Bell Labs in the 1970s, established many key operating system concepts that live on in Linux today, such as a modular architecture, hierarchical file system, and treating devices like files. Linux follows Unix design principles but was written entirely from scratch by Torvalds and other contributors. It contains no proprietary Unix code.

4. Linux uses a monolithic kernel architecture.

There are different possible designs for an operating system kernel. Linux uses a monolithic architecture, meaning that the kernel itself handles key functions like memory management, process scheduling, and system calls. This is in contrast to a microkernel architecture where the kernel is minimal and most functions are offloaded to other programs.

5. The Linux kernel is written mostly in C.

Torvalds chose to write Linux in the C programming language due to its low-level power and portability. C allows efficient interaction with hardware and is supported across many systems. Some small portions of Linux are written in assembly for performance or hardware support.

6. The Linux mascot is a penguin named Tux.

Tux the penguin has been the official mascot of Linux since 1996. Torvalds had a fondness for penguins and felt that the flightless birds shared some key qualities with Linux, like being sleek and efficient. Several variations of Tux artwork have emerged over the years.

7. Linux is the largest collaborative software project ever.

Since its early days, Linux development has been a global effort involving thousands of programmers. Changes to the kernel have come from developers in over 200 companies as well as volunteer coders. On average, a new version of the Linux kernel is released every 2-3 months with hundreds of contributors and thousands of changes.

8. Linux is a prime example of open-source software.

One key reason Linux has been able to attract so many developers is that it is open source. The Linux source code is freely available online for anyone to examine, use, modify, and redistribute under open licenses like the GNU General Public License. This has enabled Linux to tap into the power of collaborative development and grow rapidly.

9. Linux powers all of the world‘s top 500 supercomputers.

Linux absolutely dominates supercomputing. As of 2016, literally 100% of the world‘s 500 most powerful supercomputers run some flavor of Linux. The flexibility, power, and cost-effectiveness of Linux have made it the go-to choice for high-performance computing in research, academia, and industry.

10. Most web servers run on Linux.

The majority of web servers powering sites and services across the Internet are running Linux, typically the Apache web server on a Linux distro. Industry estimates suggest that around 70% of web servers run Linux, compared to about 20% for Windows. Low cost and high stability make Linux a popular choice for web hosting.

11. Android is based on the Linux kernel.

While Android has its own custom user space, the core of Google‘s hugely popular mobile operating system is the Linux kernel. Android‘s Linux foundations allow it to tap into hardware support and a wealth of existing open source code. Every time you use an Android smartphone or tablet, you‘re benefiting from Linux.

12. Even Microsoft now uses and supports Linux.

For many years, Microsoft was a fierce opponent of Linux, with former CEO Steve Ballmer once calling it a "cancer." But in a stunning turnaround, Microsoft has now embraced Linux across its business, from bringing Linux subsystems to Windows to using it to power its Azure cloud platform. In 2016, Microsoft became a Platinum member of the Linux Foundation.

13. Linux has a modular design with a central kernel.

One of Linux‘s key strengths is its modular architecture based around a monolithic kernel. The Linux kernel handles core system functions like memory management and process control. Additional functionality is provided by separate programs, drivers, and libraries that interface with the kernel. This allows different components to be swapped out or modified independently.

14. Many essential Linux components come from the GNU project.

Strictly speaking, "Linux" refers only to the kernel originally developed by Torvalds. Many other crucial parts that make up a complete Linux system, such as the GNU Compiler Collection (GCC), GNU C Library (glibc), and Bash shell, come from the GNU project. GNU, started by Richard Stallman in 1983, focuses on developing free software. The proper name for a typical Linux system is actually "GNU/Linux" to credit these contributions.

15. There are hundreds of special-purpose Linux distributions.

While there are a handful of popular mainstream Linux distros like Ubuntu, Fedora, and Mint, there are also hundreds of more obscure distros designed for specific use cases. For example, there are Linux distros customized for scientific computing, education, gaming, multimedia production, security, and more. Linux‘s flexibility allows it to be endlessly customized.

16. The Linux Foundation sponsors Linux development.

The nonprofit Linux Foundation was founded in 2000 to provide a neutral home for Linux kernel development and promote the growth of Linux. It employs key developers like Linus Torvalds and Greg Kroah-Hartman, oversees the Linux trademark, and hosts conferences and training. Over 200 companies are members of the Linux Foundation.

17. Linux powers the Large Hadron Collider.

The world‘s largest particle accelerator, the Large Hadron Collider at CERN in Switzerland, relies on Linux to crunch the massive amounts of data it generates while smashing atoms. The Worldwide LHC Computing Grid, which analyzes LHC data, is comprised of hundreds of server farms running Linux.

18. The International Space Station switched from Windows to Linux.

In 2013, the United Space Alliance, which manages the computer systems on the International Space Station, made the decision to switch ISS laptops from Windows to Linux. They found Linux to be more stable and reliable for their needs. Linux now powers many of the systems used by astronauts in space.

19. Major Hollywood films use Linux for visual effects.

The Linux operating system plays a starring role in major Hollywood productions. Movie studios like Pixar, DreamWorks, Weta Digital, and Industrial Light & Magic all use large Linux clusters for 3D modeling, animation, and visual effects. Hit films like Avatar, The Lord of the Rings, Titanic, and many Pixar classics were rendered on Linux.

20. The New York Stock Exchange runs on Linux.

When the New York Stock Exchange (NYSE) decided to modernize its trading platform in 2007, it chose Linux. NYSE Euronext‘s new Linux-based system can process millions of transactions per second with sub-millisecond latency. Other stock exchanges like the London Stock Exchange and Japan‘s Tokyo Stock Exchange also rely on Linux for fast, reliable trading.

21. Much of the public cloud runs on Linux.

Linux powers much of the infrastructure behind cloud computing. Public cloud platforms like Amazon Web Services, Google Cloud Platform, and Microsoft Azure all heavily use Linux in their data centers. When you upload files to cloud storage or run a web app in the cloud, there‘s a good chance Linux is working behind the scenes.

22. The majority of embedded systems use Linux.

Linux isn‘t just for servers and desktops. It‘s also hugely popular as an embedded operating system for limited-function devices. Because it‘s free, customizable, and well-supported, Linux is used in everything from consumer electronics to medical devices, automobiles, airplane entertainment systems, and more. Your smart TV or Wi-Fi router is probably running Linux under the hood.

23. Over 95% of the world‘s top one million websites use Linux.

An estimated 96.3% of the top one million web domains run on Linux, according to technology survey site W3Techs. Along with web servers, Linux dominates other parts of the web stack. For example, the popular LAMP stack (Linux, Apache, MySQL, PHP/Perl/Python) is one of the most common platforms for web applications.

24. Several governments and militaries rely on Linux.

Linux has found favor with a number of governments and militaries around the world due to its security, flexibility, and low cost. For example, the U.S. Department of Defense is a heavy user of Linux, with Linux servers used in the Army, Navy, and Air Force. Other governments like Russia, China, France, and Brazil have also embraced Linux.

25. Without Linux, the tech world would look very different today.

It‘s hard to overstate the impact that Linux has had on the technology landscape over the past 25 years. Without Linux, we might not have smartphones as we know them, or the expansive public cloud platforms that startups rely on. Supercomputers might be less powerful, embedded devices less flexible, and the web less stable. Linux has democratized infrastructure and enabled developers around the world.

Looking Ahead to the Next 25 Years

As we celebrate 25 years of Linux, it‘s exciting to think about what the next 25 years might hold. One thing is for sure – Linux isn‘t going anywhere. The operating system has already reshaped computing, and it will continue to evolve and adapt to new challenges.

Linux has a bright future in growing areas like cloud computing, big data, artificial intelligence, and the Internet of Things. As more devices come online and more data flows through our systems, flexible and scalable platforms built on Linux and open source software will become increasingly essential.

At the same time, the collaborative development model that has propelled Linux will keep pushing the OS forward. Programmers around the globe will continue to contribute fixes and features, while companies increasingly see the value of investing in open source.

So, here‘s to 25 years of Linux, and to the open source developers and companies who have made it a success. The little hobby project that Linus Torvalds started in his dorm room has exceeded all expectations and changed the world. I can‘t wait to see where Linux goes in the next quarter-century.