LPI OSS Essentials key terms

A licensing rule requiring anyone who distributes a modified version of a work to release it under the same license, so derivative works stay open. GPL and AGPL are common examples.

A license granting broad reuse rights with few conditions, typically only attribution and a warranty disclaimer. It allows modified versions to be redistributed under different, even proprietary, terms.

A new work created by modifying, adapting, translating, or combining an existing copyrighted work. Whether a piece of software counts as derivative determines which license obligations apply.

The GNU General Public License, a strong copyleft license created by the Free Software Foundation. Version 3 adds patent and anti-lockdown provisions. Distributed derivative works must remain under the GPL.

The Lesser General Public License, a weaker copyleft license designed for libraries. It permits linking with proprietary software when the library can be replaced, while modifications to the library itself must stay open.

A permissive license that also includes an explicit patent grant, trademark rules, and notice-file requirements. It is incompatible with GPLv2 but compatible with GPLv3.

A very short permissive license that requires only preservation of the copyright notice and license text. It is widely used because it imposes minimal obligations on redistributors.

A family of permissive licenses from Berkeley. The two-clause version requires attribution only; the three-clause version adds a rule forbidding use of contributor names for endorsement without permission.

The condition in which obligations of two or more licenses can be satisfied simultaneously when works are combined. Incompatibility, such as GPLv2 with Apache 2.0, prevents lawful merging of the code.

A business practice of releasing software under both a copyleft open source license and a paid proprietary license. Customers who cannot accept copyleft terms buy the commercial option instead.

A clause in which contributors promise not to assert patents covering their contributions against users of the software. Apache 2.0 and GPLv3 include such clauses; BSD and MIT do not.

Combining software components so they form a single executable. Static linking embeds library code and is often treated as creating a derivative work; dynamic linking is generally regarded more leniently under weak copyleft.

The Free Software Foundation's four freedoms: run the program for any purpose, study and change it, redistribute copies, and distribute modified versions. Access to source code is a precondition.

Ten criteria maintained by the Open Source Initiative that a license must meet, including free redistribution, source code availability, and no discrimination against persons or fields of use.

A license that the Open Source Initiative has reviewed and certified as conforming to the Open Source Definition. The approval list is the usual reference for judging whether software is genuinely open source.

A family of standardized public licenses for creative works such as text, images, audio, and data. Variants combine conditions like attribution, share-alike, and non-commercial use.

The Creative Commons Attribution license, the most permissive standard CC license. Reusers may copy, modify, and redistribute the work, including commercially, provided they credit the creator.

Creative Commons Attribution-ShareAlike, which adds a copyleft condition to attribution. Adaptations must be released under the same or a compatible license, similar in spirit to software copyleft.

A license condition requiring adaptations of a work to be distributed under the same terms as the original. It preserves openness of derivative works in content licensing.

A license restriction forbidding use of a work primarily intended for commercial advantage or monetary compensation. Works carrying it are not considered open source or free cultural works.

The requirement to credit the original creator, usually by name, title, and license reference. It appears in nearly every open content and permissive software license.

The status of works not protected by copyright, either because protection expired, was waived, or never applied. Anyone may use such works without permission, though other rights may still apply.

A Creative Commons public domain dedication tool. It waives copyright to the extent law allows and provides a fallback license, letting creators release works for unrestricted reuse.

Data published with a license permitting anyone to access, use, and redistribute it, often with attribution. Open government data and research datasets commonly use Creative Commons or similar terms.

A business model in which a company develops open source software and earns revenue from services, support, hosting, or proprietary add-ons rather than from license fees for the core product.

A model where a free open source core product is complemented by paid proprietary features or editions. It can generate revenue but risks tension with community expectations of full openness.

Software as a Service: delivering software over the network instead of installing it locally. Because users do not receive the software, strong copyleft like GPLv2 does not force them to share modifications.

The Affero General Public License, a GPL variant whose network-use clause requires operators of modified software offered over a network to make the source available to users.

Earning revenue by selling consulting, training, integration, or guaranteed support for software that is given away under an open source license. Red Hat popularized this approach.

Charging customers a recurring fee for access to updates, support, certifications, or hosted services around open source software, while the code itself remains freely available.

A document in which a contributor grants a project the rights to use and relicense their contribution. It clarifies provenance but can raise concerns about corporate control.

A lightweight statement, added as a Signed-off-by line in commits, that the contributor has the right to submit the code under the project's license. It is an alternative to a formal agreement.

The documented structure of decision-making in a project: who sets direction, how maintainers are chosen, and how disputes are resolved. Models range from single-vendor to meritocratic to foundation-led.

A contributor with responsibility for reviewing and merging changes and steering a project's direction. Maintainer burnout and succession are common sustainability risks.

The number of team members who could become unavailable before a project stalls. A low bus factor signals concentration of knowledge and is a recognized sustainability risk.

A public plan describing intended features, releases, and priorities over time. Publishing one helps contributors and users align expectations with project direction.

A system that records changes to files over time so contributors can review history, branch, and merge work. Git and Subversion are widely used in open source projects.

A copy of a repository that a contributor can modify independently, or, socially, a permanent split of a project into competing versions. The two meanings matter in community discussions.

A proposal to merge changes from one branch or fork into another, carrying discussion and review. It is the central collaboration mechanism in platforms like GitHub and GitLab.

The practice of having other contributors examine proposed changes for correctness, style, security, and fit with project goals before they are merged.

An email-based discussion channel used by many long-running projects for development, announcements, and archives. It remains common in projects that predate web collaboration platforms.

A system for recording bugs, feature requests, and tasks, with status and discussion. It serves as the public work queue for many open source projects.

A non-profit organization that holds trademarks, copyrights, and infrastructure for projects, aiming to keep governance neutral and vendor-independent. Examples include the Linux Foundation and Apache Software Foundation.

The process of planning, building, testing, and publishing versions of software, including version numbering, changelogs, and support windows for older releases.

The human-readable form of software written in a programming language. Access to it is a precondition for studying, modifying, and redistributing software under open licenses.

Delivering compiled executables rather than source code. Open licenses typically require that recipients can still obtain the corresponding source for such binaries.

Tooling that compiles source code, resolves dependencies, and produces artifacts. Examples include Make, CMake, Maven, and Gradle; reproducible builds are a related goal.

A tool that installs, upgrades, and resolves dependencies for software packages, such as apt, dnf, npm, pip, and cargo. It also tracks license and version metadata.

An external library or component that software relies on to function. Each added dependency brings its own license terms and must be compatible with the project's license.

A storage location for source code and its history, or for packaged software. A source repository holds commits and branches; a package repository hosts installable artifacts.