This is a list of operating systems. Computer operating systems can be categorized by technology, ownership, licensing, working state, usage, and by many other characteristics. In practice, many of these groupings may overlap. Criteria for inclusion is notability, as shown either through an existing Wikipedia article or citation to a reliable source. Proprietary Acorn Computers Arthur ARX MOS RISC iX RISC OS Amazon Fire OS Amiga Inc. AmigaOS AmigaOS 1.0-3.9 (Motorola 68000) AmigaOS 4 (PowerPC) Amiga Unix (a.k.a. Amix) Amstrad AMSDOS Contiki CP/M 2.2 CP/M Plus SymbOS Apple Inc. Apple II family Apple DOS Apple Pascal ProDOS GS/OS GNO/ME Contiki Apple III Apple SOS Apple Lisa Apple Macintosh Classic Mac OS A/UX (UNIX System V with BSD extensions) Copland MkLinux Pink Rhapsody macOS (formerly Mac OS X and OS X) macOS Server (formerly Mac OS X Server and OS X Server) Apple Network Server IBM AIX (Apple-customized) Apple MessagePad Newton OS iPhone and iPod Touch iOS (formerly iPhone OS) iPad iPadOS Apple Watch watchOS Apple TV tvOS Embedded operating systems A/ROSE bridgeOS iPod software (unnamed embedded OS for iPod) Unnamed NetBSD variant for Airport Extreme and Time Capsule Apollo Computer, Hewlett-Packard Domain/OS – One of the first network-based systems. Run on Apollo/Domain hardware. Later bought by Hewlett-Packard. Atari Atari DOS (for 8-bit computers) Atari TOS Atari MultiTOS Contiki (for 8-bit, ST, Portfolio) BAE Systems XTS-400 Be Inc. BeOS BeIA BeOS r5.1d0 magnussoft ZETA (based on BeOS r5.1d0 source code, developed by yellowTAB) Bell Labs Unix ("Ken's new system," for its creator (Ken Thompson), officially Unics and then Unix, the prototypic operating system created in Bell Labs in 1969 that formed the basis for the Unix family of operating systems) UNIX Time-Sharing System v1 UNIX Time-Sharing System v2 UNIX Time-Sharing System v3 UNIX Time-Sharing System v4 UNIX Time-Sharing System v5 UNIX Time-Sharing System v6 MINI-UNIX PWB/UNIX USG CB Unix UNIX Time-Sharing System v7 (It is from Version 7 Unix (and, to an extent, its descendants listed below) that almost all Unix-based and Unix-like operating systems descend.) Unix System III Unix System IV Unix System V Unix System V Releases 2.0, 3.0, 3.2, 4.0, and 4.2 UNIX Time-Sharing System v8 UNIX Time-Sharing System v9 UNIX Time-Sharing System v10 Non-Unix Operating Systems: BESYS Plan 9 from Bell Labs Inferno Burroughs Corporation, Unisys Burroughs MCP Commodore International GEOS AmigaOS AROS Research Operating System Control Data Corporation Lower 3000 series SCOPE (Supervisory Control Of Program