Almost every moment you use the internet, you use software nobody bought. Most of the world's servers run Linux, Android is built on it, and roughly two in five websites are built on WordPress. All of these are 'open source'. So what is it, and how does software given away for free hold up a trillion-dollar industry?
Open source is software whose code, the 'recipe' it is built from, is visible to all. Anyone can read it, use it, change it and usually distribute their own version, subject to the license. It is the opposite of 'closed' software, where only the company that built it sees the code. Linux, for example, was created in 1991 by a Finnish student named Linus Torvalds and has since been built by thousands of developers worldwide, some volunteers and some employed by companies that fund the work.
Why do companies give code away? Because it pays. Instead of every company building its own operating system, they all use the same foundation and invest in improving it, saving billions. The money comes from what is built on top: cloud services, support, commercial products. Israeli companies are built on open source too; JFrog, for example, grew out of the need to manage the countless open components modern software is made of. And OpenAI, announcing this week that it will buy Pierre, promised the company's open-source libraries will stay open.
But the model has a weak point: people. Many critical projects are maintained by small groups, sometimes one or two people, who review every change, fix every flaw and answer every report. AI now adds new pressure. AI tools find vulnerabilities at an unprecedented pace: OpenAI reported this week 948 Linux kernel flaws found by agents. That is good for security, but someone has to review and fix it all. Linux maintainers have already complained this year of a wave of reports that is hard to keep up with.
What does it mean for you? That the internet's safety depends heavily on people most of the world has never heard of. When a big company funds maintainers, contributes code or helps fix flaws, it is not doing a favor; it is protecting the foundation it is built on. And the next time your phone or website asks to install an update, remember that behind it there are often volunteers who worked to close a hole you never knew existed.
