The Open Source Definition

The Open Source Definition (OSD) is a document published by the Open Source Initiative. Derived from Bruce Perens' Debian Free Software Guidelines, the definition is the most common standard for open-source software. The definition has ten criteria, such as requiring freely accessed source code and granting the open-source rights to everyone who receives a copy of the program. Covering both copyleft and permissive licenses, it is effectively identical to the definition of free software, but motivated by more pragmatic and business-friendly considerations. The Open Source Initiative's board votes on proposals of licenses to certify that they are compliant with the definition, and maintains a list of compliant licenses on its website. The definition has been adapted into the Open Knowledge Foundation's Open Definition for open knowledge and into open hardware definitions.

History
As Netscape released the open-source Mozilla browser in 1998, Bruce Perens drafted a set of open-source guidelines to go with the release. A modified version of this definition was adopted by the Open Source Initiative (OSI) as the Open Source Definition. The OSI uses the label "open source", rather than "free software", because it felt that the latter term had undesirable ideological and political freight, and it wanted to focus on the pragmatic and business-friendly arguments for open-source software. It adopted a closed rather than membership-driven organizational model in order to draft the definition and work together with a wider variety of stakeholders than other free or open-source projects.

Criteria
Providing access to the source code is not enough for software to be considered "open-source". The Open Source Definition requires that ten criteria be met:
 * 1) Free redistribution
 * 2) Source code must be accessible and the license must permit redistribution in the form of source code (rather than object code). In order to modify the software, access to source code is required.
 * 3) Derivative works must be allowed and able to be redistributed under the same licensing terms as the open-source product
 * 4) The license may require that the original software be distributed intact, but only if modifications are able to be distributed as patches without restriction.
 * 5) No discrimination between users
 * 6) No discrimination between uses, including commercial use
 * 7) Everyone who receives a copy of the program is granted all the open-source rights
 * 8) The license must cover all the code, not a particular product or distribution.
 * 9) There may not be restrictions on other software distributed at the same time
 * 10) Technological neutrality—cannot restrict use to any particular technology. For example, a license that requires a user to click a box agreeing to it is not free because the work cannot be distributed as a paper copy.

The Open Source Definition is available under a Creative Commons (CC BY 4.0) license. It covers both copyleft—where redistribution and derivative works must be released under a free license—and permissive licenses—where derivative works can be released under any license. It is part of the open source movement rather than the free software movement, and seeks to promote the availability of open-source software for anyone seeking to reuse it, even the makers of proprietary software. It does not address warranty disclaimers, although these are very common in open-source software. The definition does not specify a governance structure for open-source projects.

Compliant licenses
The criteria are used by the OSI to approve certain licenses as compatible with the definition, and maintain a list of compliant licenses. New licenses have to submit a formal proposal that is discussed by the OSI mailing list before it is approved or rejected by the OSI board. Seven approved licenses are particularly recommended by the OSI as "popular, widely used, or having strong communities":


 * Apache License 2.0
 * BSD 3-Clause and BSD 2-Clause Licenses
 * All versions of the GNU General Public License
 * All versions of the GNU Lesser Public License
 * MIT License
 * Mozilla Public License 2.0
 * Common Development and Distribution License (CDDL)
 * Eclipse Public License version 2.0

Reception
The Open Source Definition is the most widely used definition for open-source software, and is often used as a standard for whether a project is open source. It and the official definitions of free software by the Free Software Foundation (FSF) essentially cover the same software licenses. Nevertheless, there is a values difference between the free software and open source movements: the former is more based on ethics and values, the latter on pragmatism.

Derived definitions
The Open Knowledge Foundation's Open Definition is substantially derivative of the Open Source Definition.

The Open Source Hardware Statement of Principles is adapted from the Open Source Definition.