Explained · 2 min
What does "open source" mean?
Why open source is about rights, not just being able to see the code.
Written by AI and checked against our editorial standards. Not reviewed by a human editor.
Open source software comes with its source code, the human-readable instructions behind the program. Its licence lets anyone use, change and share that code.
The Open Source Initiative keeps the official checklist, called the Open Source Definition. It has ten points. You must be allowed to give the software away or sell it, without paying fees. The source code must be included. You must be allowed to change it and share your version. And the licence may not shut out any person, group or field of work, such as business or research.
Think of it like this: a closed program is a cake from a bakery. You can eat it, but not see how it was made. Open source is the recipe, with written permission to cook it, change it and hand out copies, even in your own shop.
That is also why open source is more than “you can look at the code”. The definition says it directly: open source does not just mean access to the source code. A licence that bans, for example, use by large companies is not open source, even if the code is public. Popular open source licences include MIT and Apache 2.0.
For AI, the word gets used loosely. A model can be “open-weight” (you can download it) without its training data or code being shared. That is not the same thing.
Why it matters to you: anyone can check open source tools, and others can keep them alive if the maker stops. The price is that support and security are often up to you.
Learn more: Open Source Initiative: The Open Source Definition