To most people open source means free software.
Anyone can download this kind of software without paying a fee. It doesn’t break any laws. You have the original developer’s permission to use it.
You can run the software, copy it and pass it on to friends and colleagues.
Free software is only part of the story. It isn’t the most important thing about open source. Yet free software is liberating.
Open source lets you look at code
What matters more is that you can look at the code used to write the software. This means you can see how the developers made the program.
If you have coding skills you can figure out what the developers did. You may be able to understand the assumptions and decisions they made when they wrote the code.
You can tinker with the code and release your own customised version.
Or perhaps you might spot a flaw or an area where the original developers could have done something better. When that happens you can send what you found to the developers and have them fix it, or you can fix it yourself and send them the improved version.
This is how software evolves and improves over time. The same process can work with software that isn’t open, but letting everyone interested take a look speeds things up and often means better results.
When you tinker with, improve or fix open source software, you are expected to make your new version as freely available as the original. That way others can follow your work, improve or fix it.
This is a virtuous circle.
Any piece of code can be open source. There are libraries of code snippets you can use to perform simple tasks or include in your own projects.
There are applications and even operating systems. Some of the best known software is based on open source.
While ‘free’ is an important part of the philosophy, there can be open source paid-for software. That is you can look at the code, but you have to pay to use it. The money is often used to pay for further development.
This approach has many of the same benefits. It means that people and companies can earn a living at the same time.
There are also many commercial and semi-commercial products and services that are build on open source foundations.
The opposite to open source software is often known as proprietary software. You can think of this as closed source. It is where someone, usually a company, owns the intellectual property. In some cases this can include patents.
As a rule you don’t get to see proprietary code and you pay to use the software. Until about 30 years ago all software was proprietary. A lot of enterprise and software used by government still is.