Proprietary software
Proprietary software is
software that has restrictions on using and copying it, usually enforced by a
proprietor. The prevention of use, copying, or modification can be achieved by legal or technical means. Technical means include releasing machine-readable
binaries only, and withholding the human-readable
source code. Legal means can involve
software licensing,
copyright and
patent law. Proprietary software can be sold for money as
commercial software or available at zero-price as
freeware. According to the
Free Software Foundation (FSF), 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 the software. This could include any software that is not in the
public domain, including free software with existing
copyrights. The FSF 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.
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 term "non-free software" (or "nonfree") 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, but they too sometimes talk of "proprietary software". The
Open Source Initiative prefers the term "
closed source software".
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.
Like freeware,
shareware is proprietary software available at zero price for a trial period. 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.
Well known examples of proprietary software include
Microsoft Windows,
RealPlayer,
Adobe Photoshop,
Mac OS,
WinZip and some versions of
UNIX.
*
Non-proprietary software*
Software hoarding*
Vendor lock-in
