Definition of open-source software

Summary

Open-source software (OSS) is computer software whose source code is publicly available, enabling users to use, study, modify, and distribute it. This is typically made possible through licenses that meet the Open Source Initiative’s Open Source Definition (OSD), which includes requirements such as non-discrimination and permission to reuse and redistribute the software. In contrast, proprietary (closed-source) software does not provide users with access to its source code and restricts modification and redistribution. The meaning of “open source” is also debated. While OSS is commonly defined by the OSD, the term is not legally controlled by the OSI and remains a matter of social convention, leading to disputes sometimes described as a “culture war” within software communities. These conflicts are influenced by ethical and commercial concerns and can result in the term being used in ways that do not fully match the OSD. Related concepts include “free software” (emphasizing user freedoms rather than price) and “source-available” software (where source code is visible but may not grant the full rights required for OSS).

Key Points

• 1

  OSS is defined by publicly available source code and licenses that allow use, modification, and redistribution, commonly guided by the OSI’s Open Source Definition.

• 2

  The term “open source” is subject to controversy and semantic conflicts, including disagreements with the free software movement and questions about whether certain categories (e.g., public-domain or source-available software) truly qualify as OSS.

• 3

  Open-source development often follows collaborative, decentralized models, and OSS adoption is widespread in modern digital infrastructure, but it also raises cybersecurity and maintenance challenges.