What is open-source software?

Open-source software (OSS) is software whose source code is made publicly available under a license that allows anyone to view, modify, and distribute it. Unlike proprietary software, where the code is restricted and owned by a single entity, open-source projects are built collaboratively by communities of developers. The defining feature is the license—such as the GNU General Public License (GPL) or MIT License—which grants users legal permission to study, adapt, and share the code. For example, the Linux operating system and the Apache web server are foundational open-source projects that power much of the internet and enterprise systems today. This model emphasizes transparency, enabling developers to inspect how software works and verify its behavior.

The collaborative nature of open-source development fosters innovation through shared contributions. Developers worldwide can submit improvements, report bugs, or suggest features, often using platforms like GitHub or GitLab. Projects like Kubernetes, originally developed by Google and now maintained by the Cloud Native Computing Foundation, thrive on contributions from individuals and companies. Companies like Red Hat and IBM actively participate in open-source ecosystems, contributing code to projects like the Linux kernel while building commercial services around them. This decentralized approach allows problems to be solved faster, as diverse perspectives and expertise are applied. For instance, security vulnerabilities in critical tools like OpenSSL are often identified and patched by community members, reducing risks for all users.

For developers, open-source software offers practical advantages. It provides access to high-quality tools without licensing costs, such as the Python programming language or the React library for building user interfaces. Developers can customize software to fit specific needs—like modifying WordPress plugins for a unique website requirement—or learn from real-world codebases to improve their skills. Open-source also avoids vendor lock-in; for example, using PostgreSQL as a database ensures flexibility compared to proprietary alternatives. Additionally, many modern technologies, such as TensorFlow for machine learning or Docker for containerization, are open-source, making them integral to development workflows. By participating in open-source projects, developers gain visibility, build professional networks, and contribute to tools they rely on daily.