Introduction of Proprietary software

The term "proprietary software" is often used to mean computer software which is neither free nor open source (as these terms are variously defined, especially by FOSS advocates such as the Free Software Foundation and the Open Source Initiative). Terminology for forms of software licensing is not fully standardized and can be controversial. A literal meaning of "proprietary" in relation to software is that it has a copyright owner who can exercise control over what users can do with the software, in contrast to public domain. However, the term is commonly used in a narrower sense to describe software with restrictions on use or private modification, or with restrictions judged to be excessive on copying or publishing of modified or unmodified versions. These restrictions are placed on it by one of its proprietors. In this sense it is also known as "non-free software" and is the opposite of free software, generally speaking.

A related term is "closed-source software" which usually describes software whose source code is not published, in contrast with "open source". While most proprietary software is closed-source, source-available proprietary software also exists. Some kinds of software (such as shared source and "public source") are neither "closed-source" nor "open source" according to narrow definitions of those terms.

Legal meanings and licensing

Exclusive legal rights to software by a proprietor are not required for software to be proprietary. Software which is not proprietary, like public domain software and software under a permissive licence, can become proprietary software by distributing compiled, binary versions of the program without making the source code available.

The free software movement's founder Richard Stallman sometimes uses the term "user-subjugating software" to describe proprietary software, while Eben Moglen sometimes talks of "unfree software". The term "non-free" is often used by Debian developers to describe any software whose license does not comply with Debian Free Software Guidelines, and they use "proprietary software" specifically for non-free software that provides no source code. The Open Source Initiative uses the terms "proprietary software" and "closed source software" interchangeably.

Semi-free software, as defined by the Free Software Foundation, is software that is not free software, but comes with permission for individuals to use, copy, distribute, and modify (including distribution of modified versions) only for non-profit purposes. Such software is also rejected by the Open Source Initiative and Debian. PGP and Angband are examples of semi-free programs. The Free Software Foundation classifies semi-free software as non-free software, but draws a distinction between semi-free software and proprietary software.

Free software licences use the same laws used by proprietary software, but to preserve the rights to use, copy and modify the software. This technique is used with copyleft, but with other software as well. Free software companies and projects are also joining into patent pools like the Patent Commons and the Open Invention Network. See software patents and free software.

"Proprietary software" is not synonymous with "commercial software", though the industry commonly confuses the term, as does the free software community.

Proprietary software can be distributed at no cost or for a fee, and free software can be distributed at no cost or for a fee. The difference is that whether or not proprietary software can be distributed, and what the fee would be, is at the proprietor's discretion. With free software, anyone who has a copy can decide whether, and how much, to charge for a copy or related services.

Proponents of commercial proprietary software argue that requiring users to pay for software as a product increases funding for the research and development of software. For example, Microsoft says that per-copy fees maximise the profitability of software development.

Proprietary software is said to create greater commercial activity over free software, especially in regard to market revenues.

A dependency on the future versions and upgrades for a proprietary software package can create "vendor lock-in", entrenching a monopoly position. If the proprietor of a software package should cease to exist, or decide to cease or limit production or support for a proprietary software package, recipients and users of the package may have no recourse if problems are found with the software. Proprietors can fail to improve and support software because of business problems. When no other vendor can provide support for the software, the ending of support for older or existing versions of a software package may be done to force users to upgrade and pay for newer versions; or migrate to either competing systems with longer support life cycles or to FOSS-based systems.