Proprietary Software

[Luis Fok]

Proprietary is an adjective that describes something owned by a specific company or individual. In the computing world, proprietary is often used to describe software that is not open source or freely licensed. Examples include operating systems, software programs, and file formats.
Proprietary operating systems cannot be modified by users or other companies. For example, Windows and OS X are both proprietary OSes. The Windows source code is owned by Microsoft and the OS X source code is owned by Apple. Other companies can make programs that run on these operating systems, but they cannot modify the OS itself. Linux and Android are not proprietary, which is why many different versions of these operating systems exist.
Proprietary software programs are applications in which all rights are retained by the developer or publisher. They are typically closed-source, meaning the developer does not provide the source code to anyone outside the company. Proprietary programs are licensed to end users under specific terms defined by the developer or publisher. These terms often restrict the usage, distribution, and modification of the software. Most commercial software is proprietary because it gives the developer a competitive advantage.
Some file types are saved in a proprietary file format that can only be recognized by a specific program. These file types are typically created by proprietary software programs and are usually saved in a binary (rather than a text-based) format. By storing data in a proprietary format, developers can ensure that files created with their software cannot be opened with other software programs. Proprietary file types saved by software programs are also called native files.

[Magaret]

[Software] that is not [free software] or semi-free [software] (the same thing as free software except that it can only be used for [non-profit] things).

[Mark Zuckerberg]

Something said to be [evil], [yet] [nobody knows] why.