These tables compare free software / open-source operating systems. Where not all of the versions support a feature, the first version which supports it is listed.

(operating systems)

An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.

<operating system> (OS) The low-level software which handles the interface to peripheral hardware, schedules tasks, allocates storage, and presents a default interface to the user when no application program is running. The OS may be split into a kernel which is always present and various system programs which use facilities provided by the kernel to perform higher-level house-keeping tasks, often acting as servers in a client-server relationship. Some would include a graphical user interface and {window system} as part of the OS, others would not. The {operating system loader}, BIOS, or other firmware required at {boot time} or when installing the operating system would generally not be considered part of the operating system, though this distinction is unclear in the case of a {rommable operating system} such as RISC OS. The facilities an operating system provides and its general design philosophy exert an extremely strong influence on programming style and on the technical cultures that grow up around the machines on which it runs. Example operating systems include 386BSD, AIX, AOS, Amoeba, Angel, Artemis microkernel, BeOS, Brazil, COS, CP/M, CTSS, Chorus, DACNOS, DOSEXEC 2, GCOS, GEORGE 3, GEOS, ITS, KAOS, Linux, LynxOS, MPV, MS-DOS, MVS, Mach, Macintosh operating system, Microsoft Windows, MINIX, Multics, Multipop-68, Novell NetWare, OS-9, OS/2, Pick, Plan 9, QNX, RISC OS, STING, System V, System/360, TOPS-10, TOPS-20, TRUSIX, TWENEX, TYMCOM-X, Thoth, Unix, VM/CMS, VMS, VRTX, VSTa, VxWorks, WAITS. {FAQ (ftp://src.doc.ic.ac.uk/usenet/news-info/comp.os.research)}. Usenet newsgroup: news:comp.os.research. [Jargon File] (1999-06-09)

<standard> (OSD) Definition of distribution terms for {open source} software, promoted by the Open Source Initiative. http://opensource.org/osd.html. (1999-11-28)

Open-source software security is the measure of assurance or guarantee in the freedom from danger and risk inherent to an open-source software system.

The Open Source Definition is a document published by the Open Source Initiative, to determine whether a software license can be labeled with the open-source certification mark.

Open-source software development (OSSD) is the process by which open-source software, or similar software whose source code is publicly available, is developed by an open-source software project. These are software products available with its source code under an open-source license to study, change, and improve its design.