There are many open-source software programs that serve a number of applications. There are also many different open-source licenses. Broadly speaking, open-source software can be used, modified and shared legally in many environments and contexts. However, different licenses come with different agreements, and it’s important to understand the distinctions between each major license in order to get the most out of open-source software, as well as get a broad sense of the open-source movement and its purpose. (To learn more, see Open Source: Is It Too Good to Be True?)

The Source of Open Source

Although the term “open source” was coined in 1998, the origins of the free software movement date back as far as the 1970s. Software developer, hacker and free software activist, Richard Stallman, was developing a free and open operating system by 1983. In early 1984, he announced the GNU Project, which developed an operating system that was largely inspired by Unix (GNU is a recursive acronym for “GNU’s Not Unix”) but with source code that was free and open to the public for the proposed greater good of the community.

GNU employed a philosophy pioneered by Stallman (as well as other anti-copyright activists) known as “copyleft,” which essentially acknowledged the copyright privileges legally bestowed upon original intellectual property, but expressly waived them in order to promote open use and development of the work. This technique and philosophy granted free access to source code for software released under copyleft, for free and open use and modification.

The rise of the Linux kernel and operating system in the 1990s inspired the development of the Apache Web Server, a free and open HTTP server whose unprecedented popularity many theorize validated many of the philosophies and efforts of the free software movement, and endeared the free software ethos to the mainstream. It remained among the most widely used Web servers well into the next two decades, and many consider it to have played a key role in the early development of the website.

Shortly thereafter, the browser wars of the mid to late 1990s prompted Netscape to release their Communicator 4.0 source code to the public under a license agreement similar to that of GNU, but with allowances for the company to develop proprietary software based on the code. This marked the beginning of the open-source movement as we know it today. (To learn more about women in open source, see Why There Aren't More Women Working in Open Source Software.)

Types of Licenses

As open source continues to evolve as an organized movement and set of standards, new license agreements are created and tailored to the needs of different users and work environments. In order to be approved by the Open Source Initiative (OSI) a license must be submitted by request, along with some supporting material, to the OSI License Review community.

The community (ideally with the participation of the submitter) will then discuss the license and become familiar with its goals, ideals and conditions. The License Review Chair will then present recommendations to the OSI Board, who ultimately decide whether or not the license goes into effect. There are many different open-source licenses, but here are some examples with brief descriptions of their purpose and function:

Mozilla Public License 2.0

The Mozilla Public License 2.0 is a simple copyleft license. It is often referred to as a "middleground" between the GNU (which is restrictive) and the Apache (which is liberal) licenses. Restrictions are placed on how and in what manner source code is shared in the broader community. More restrictions apply for the source being shared outside of the licensee’s organization than within, for example, in the case of MPL 2.0. This helps ensure the source code is shared freely, while imposing as little intervention on operations within the licensee’s organization as possible.

Universal Permissive License 1.0

The Universal Permissive License was forged out of a Java Community Process discussion. Originally based on the MIT License (which is very permissive and one of the oldest open-source licenses), one of UPL’s key features is its express patent license, which ensures developers a safe platform upon which collaborators need not worry about patent infringements on simultaneous projects.

Academic Free License 3.0

The Academic Free License 3.0 was written by an attorney and computer specialist named Lawrence Rosen, who served as general counsel to the Open Source Initiative for a number of years. The license uses a very defensive strategy against parties who seek to sue for patent infringement by terminating their license once patent infringement actions are commenced against it.

Artistic License 2.0

Originally developed for the Perl programming language, Artistic License 2.0 has been regarded as ambiguous and often difficult to interpret. There have thus been several attempts to clarify the license in the form of The Artistic License Version 2.0, The Clarified Artistic License and The Modified Artistic License (MAL).

Fair License

In contrast with the Artistic License, the Fair License (not to be confused with the legal concept of "fair use") is short and simple. The short license simply reads as such: “Usage of the works is permitted provided that this instrument is retained with the works, so that any entity that uses the works is notified of this instrument. DISCLAIMER: THE WORKS ARE WITHOUT WARRANTY.” Simply enough, the license must accompany distribution of the software, while disallowing any warranties on it.

Conclusion

Although very important to understand, copyright law is immensely difficult to comprehend. The avenues and users of today's digital media and communications technology are so ubiquitous, and are expanding and diversifying in such a prolific manner, that the regulation of the transmission and commerce of intellectual property must be in a constant state of evolution. Along with other legal concepts such as copyleft and Creative Commons, open source enables users to find access to useful and beneficial resources while avoiding or minimizing the limitations of copyright.