Open source software (OSS) is software whose source code is made publicly available, allowing anyone to inspect, modify and distribute it. The term was coined in 1998 to describe software released under licences that grant these freedoms. Open source powers much of the modern internet: Linux, Apache, Nginx, MySQL, PostgreSQL, PHP, Python, Node.js, WordPress and countless other projects are open source.
Key Open Source Licences
- MIT — Very permissive. You can use, modify and distribute, even in proprietary software, as long as you include the licence notice.
- Apache 2.0 — Permissive with patent protection. Widely used by enterprise projects.
- GPL (GNU General Public License) — Copyleft. Any derivative work must also be released under the GPL ("viral" licence).
- LGPL — Like GPL but allows linking from proprietary software.
- AGPL — GPL extended to cover network-delivered software (SaaS).
Benefits of Open Source
- Free to use (in most cases).
- Community-driven improvements and security audits.
- Transparency — you can verify what the software does.
- Avoid vendor lock-in.