Proprietary software

Terminology

According to the Free Software Foundation (FSF), the group behind the GNU project, proprietary software is any software that does not meet its definitions of free software or semi-free software. The term's literal meaning covers software that has an owner who exercises control over what users can do with it. One license of the FSF's, the GNU General Public License, asserts that the restrictions of free software offer computer users freedom while the restrictions of other software benefit only the owner and are unethical. The adjective "proprietary" also avoids confusion with the phrase "commercial software", since free software can also be sold and used for commercial purposes.

The term non-free software (or just non-free) is used interchangeably and about as often by the free software movement. FSF founder Richard Stallman sometimes uses the term "user subjugating software", while Eben Moglen sometimes talks of "unfree software". The term "non-free" is generally used by Debian developers to describe any software whose license does not comply with Debian Free Software Guidelines, and use "proprietary software" specifically for non-free software that provide no source code. The Open Source Initiative prefers the term "closed source software".

Risks

If for any reason the proprietor ceases, or decides to cease, or limit production or support for a proprietary software product, previous licensees can be left at a disadvantage and have no recourse if problems are found with the software. The proprietor uses a temporary monopoly with copyright and sometimes software patents that can make the software more expensive.[citation needed] A dependency on future versions and upgrades can make the monopoly permanent without the emergence of a competing software package.

Examples

Well known examples of proprietary software include Microsoft Windows, RealPlayer, Adobe Photoshop, Mac OS, WinZip and some versions of UNIX.

Some free software packages are available under proprietary terms. Examples include MySQL, Sendmail and SSH. The original copyright holders for a work of free software, even copyleft free software, can use dual-licensing to allow themselves or others to redistribute proprietary versions. Non-copyleft free software, or free software "with a permissive license", allows anyone to make proprietary redistributions.

Some proprietary software comes with source code or provides offers to the source code. Users are free to use and even study and modify the software in these cases, but are restricted by either licenses or non-disclosure agreements from redistributing modifications or sharing the software. Examples include Pine, the Microsoft Shared source license program, and certain proprietary implementations of SSH.

Shareware, like freeware, is proprietary software available at zero price, but differs in that it is free only for a trial period, after which some restriction is imposed — for example, it is completely disabled.

Proprietary software that has a copyright that isn't enforced but is used illegally by users is called abandonware and may include source code. Some abandonware has its source code placed in the public domain either by its author or copyright holder and is therefore free software, not proprietary software.

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