Fundamentals of Open Source Software Development
This domain tests how open source projects actually produce software: the definition that makes a license open source, the collaboration model that turns strangers into co-maintainers, and the vocabulary of upstream and downstream that every later domain assumes.
The definition
The Open Source Definition (OSD) sets ten criteria, including free redistribution, availability of source code, permission for derived works, integrity of the author's source code, no discrimination against persons, groups, or fields of endeavor, and no contamination of other software. The FSF's four freedoms - run, study, redistribute, improve - describe the same territory from a user's perspective.
How projects are organized
- Roles: users, contributors, reviewers/committers, maintainers. Authority is earned through sustained contribution rather than assigned by an org chart.
- Governance ranges from a benevolent dictator to a foundation-backed technical steering committee; foundations (Apache, Eclipse, Linux Foundation, CNCF) typically hold trademarks and neutral IP.
- Work is asynchronous: issue trackers, pull/merge requests, code review, CI gates, RFC or enhancement-proposal processes, and lazy consensus.
- Releases follow a cadence and a versioning contract, usually Semantic Versioning (MAJOR.MINOR.PATCH), sometimes with long-term-support branches.
- Health is visible in community files: LICENSE, README, CONTRIBUTING, CODE_OF_CONDUCT, SECURITY, and a changelog.
Worked example
A product advertises a "community edition" licensed for "research and other non-commercial use." Criterion 1 requires free redistribution and criterion 6 forbids discrimination against fields of endeavor; a non-commercial field restriction breaks both. The code is source-available, not open source, so your organization cannot treat it as forkable or redistributable inside a commercial product.
Traps
- A public repository without a LICENSE file is all rights reserved, not open source.
- Zero price and open source are independent properties.
- A popular fork does not make the upstream healthy, and vice versa.
- A maintainer cannot relicense contributions unless a CLA or an inbound=outbound license grant covers them.