What Is Open Source Software? A Plain-English Guide

You used open source software today. I'm fairly sure of it, and I haven't met you.

If you opened a website this morning, the server that sent it to you was almost certainly running Linux. If you watched a video that wouldn't play in your usual app, you might have reached for VLC. If you searched for anything, somewhere in that chain a piece of free, openly built software did part of the work. Most of the internet quietly runs on code that anyone in the world is allowed to read, copy, and change. You just never see it, because it sits behind the screen doing its job.

So let me pull back the curtain on a phrase you've probably heard thrown around and never had explained plainly: open source software. By the end of this, it should feel less like jargon and more like something you could actually take part in.

The recipe on the wall, not the formula in the safe

Here's the cleanest analogy I know.

Imagine two restaurants. The first makes a famous sauce, and the exact recipe is locked in a safe. Only a few trusted people know it. You can buy the sauce, you can taste it, but you can never see how it's made, and you certainly can't tweak it for your own kitchen. That's closed source software. The product works, but the instructions behind it are a secret.

The second restaurant prints its full recipe on the wall. Anyone can read it, cook it at home, change the spices, and even hang their own improved version next to it. That's open source software. The "recipe" is called the source code — the human-readable instructions that tell a computer what to do — and it's published openly for anyone to inspect, use, modify, and share.

That's the whole core idea. Open source software is software whose source code is public. Usually it's free to use as well, but as we'll see, "free" is the slippery part of this story.

Free as in freedom, not just free as in price

When people first hear "open source," they think free means costs nothing. That's often true, but it misses the more important meaning.

There's an old line in this world that captures it: think free as in speech, not free as in beer. Free beer is about price. Free speech is about freedom — the right to do something. Open source is mostly about the second kind.

The freedom in question is a bundle of rights: you can run the software for any purpose, study how it works by reading the code, change it to fit your needs, and pass your version on to others. A company can absolutely charge money for open source software or for support around it. What it can't do is hide the recipe or stop you from sharing it. The price tag is optional. The openness is the point.

The open source you already lean on

This isn't a niche hobby for a few programmers. Open source quietly holds up enormous parts of daily life. A few names you'll recognise:

• Linux — an operating system, like Windows or macOS, but open. It runs the overwhelming majority of the world's web servers, and a modified version of it sits inside Android, which means a huge share of the phones on Earth.
• Firefox — a web browser built and maintained in the open.
• VLC — the friendly orange traffic-cone media player that stubbornly plays almost any video or audio file you throw at it.
• WordPress — the software behind a remarkable slice of the world's websites, from tiny personal blogs to large publications.
• Python — one of the most popular programming languages on the planet, free and open, and often the first language people learn.

None of these locked their recipe in a safe. And that openness is a big part of why they spread so far.

Who actually makes it, and why would they?

This is the question I get most. If nobody's forced to pay, who builds all this, and what's in it for them?

The honest answer is: a mix of people, for a mix of reasons. Some open source is built by volunteers in their spare time, scratching their own itch — they needed a tool, it didn't exist, so they made it and shared it. Some is built by loose communities scattered across the globe, strangers who collaborate through the internet and have never met in person. And a surprising amount is built and funded by large companies, because it's often cheaper and smarter to maintain shared infrastructure together than for each company to secretly rebuild the same thing alone.

The motivations are very human: reputation, the joy of solving a problem, wanting to learn, wanting their tools to outlive them, and yes, sometimes a salary. The result is a sprawling, messy, astonishingly productive global workshop where the doors are unlocked.

Licenses, lightly: permission slips for code

Putting code in the open doesn't mean there are no rules. Each open source project comes with a license — a short legal document that says what you're allowed to do with it. You don't need to be a lawyer here. Two families cover most of what you'll meet.

Permissive licenses, like the MIT license, are roughly: "Do almost anything you like, just keep our name on it, and don't blame us if it breaks." You can take the code, build a paid product on top of it, and you're not required to share your changes back. Easy and flexible.

Copyleft licenses, like the GPL, add one big condition: if you build on this code and share your version, your version must stay open too. The freedom is designed to be contagious. It's a clever way of making sure open code keeps spawning more open code rather than getting absorbed into locked safes.

Neither is "better." They're different philosophies about how freedom should travel. As a beginner, the thing to remember is simply: every open source project has a license, and it's worth a thirty-second read before you build on something.

Why this matters, especially from where I sit

I write this from Tanzania, and I want to be direct about why open source matters more, not less, for African developers.

It removes the price of entry. You don't need to buy expensive licensed tools to learn world-class skills — Linux, Python, and an ocean of professional software are free and on your laptop in minutes. It's the best classroom in software: you can open the actual code that powers the internet and read how the experts did it, which no textbook can match. It protects you from lock-in, where a single vendor can trap you and then raise the price. And, quietly, it's one of the most level playing fields in technology. A good contribution to an open source project is judged by the code, not by where you live or which university you attended.

I've watched people build entire careers on this. They fix a small bug in a project they use, the fix gets accepted, their name is now in the history of real, used software — and that public track record opens doors that a CV alone never could.

The honest part: it isn't free of cost

I promised plain and honest, so here's the part the cheerleaders skip.

Open source is not magic, and it's not effortless. Behind many tools you rely on is a tiny number of unpaid maintainers, sometimes a single tired volunteer, keeping critical software alive in their evenings. This is the sustainability problem: software the whole world depends on can rest on shoulders that get no money and little thanks, and burnout is real. Open source also isn't automatically more secure just because the code is visible — visibility helps, but only if people actually look. And "free to use" can still mean "expensive to maintain" once you build something serious on it.

I say this not to discourage you but to make you a good citizen of this world. If a tool helps you, consider giving back — a bug report, a fix, a kind word, or money if you have it. That's how the recipe on the wall stays cooking.

Where to begin

You don't have to write a single line of code to start. Download VLC or Firefox and notice you're already a user. Then, when you're ready, find one small open source project you genuinely use, read its code, and look for an issue labelled "good first issue." That's the open door. Walk through it.

The deeper lesson is this: a huge portion of modern technology was built by people who decided to share rather than hide. You're allowed to read it, learn from it, and add to it. That invitation is open. It's been open the whole time.

Frequently asked questions

Is open source software safe to use?

Generally, yes — much of it is more battle-tested than closed software because so many people can inspect it. But 'open' doesn't automatically mean 'secure.' Stick to well-known, actively maintained projects with healthy communities, and you're on solid ground.

If it's free, how do the people behind it make money?

Several ways. Companies sell support, hosting, or premium features built around the open core. Some maintainers are employed by businesses that depend on the software. Others rely on donations or sponsorships. And many genuinely build it for free, for reputation, learning, or love of the craft.

Can I use open source software in a business or a paid product?

Usually yes, but it depends on the license. Permissive licenses like MIT let you do almost anything, including building paid products. Copyleft licenses like the GPL require you to keep your version open if you distribute it. Always read the license first.

Do I need to be a programmer to contribute?

Not at all. Projects need writers for documentation, people who report bugs clearly, translators, designers, and testers. Some of the most valuable contributions involve no code. Reporting a problem well is a real, welcome contribution.

What's the difference between open source and just being free to download?

Plenty of software costs nothing but keeps its source code secret — that's free of price, not open source. Open source specifically means the recipe, the source code, is public and you're legally allowed to read, change, and share it.

Further reading on this site

• What Are Git and GitHub? — the tools the open source world uses to collaborate on code.
• How APIs Actually Work — another plain-English breakdown of the machinery behind modern software.
• Browse Education — more beginner-friendly explainers like this one.

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