is an open source operating system for computers. It is a Linux distribution based on the Debian architecture. It is usually run on personal computers, and is also popular on network servers, usually running the Ubuntu Server variant, with enterprise-class features. Ubuntu runs on the most popular architectures, including Intel, AMD, and ARM-based machines. Ubuntu is also available for tablets and smartphones, with the Ubuntu Touch edition.

Ubuntu is published by Canonical Ltd, who offer commercial support.[4] It is based on free software and named after the Southern African philosophy of ubuntu (literally, 'human-ness'), which Canonical Ltd. suggests can be loosely translated as "humanity to others" or "I am what I am because of who we all are".[3]

Ubuntu is the most popular operating system running in hosted environments, so–called "clouds",[5] as it is the most popular server Linux distribution.

Development of Ubuntu is led by UK-based Canonical Ltd., a company founded by South African entrepreneur Mark Shuttleworth. Canonical generates revenue through the sale of technical support and other services related to Ubuntu.[6][7] The Ubuntu project is publicly committed to the principles of open-source software development; people are encouraged to use free software, study how it works, improve upon it, and distribute it.

a version control system for tracking changes in computer files and coordinating work on those files among multiple people. It is primarily used for source code management in software development,[8] but it can be used to keep track of changes in any set of files. As a distributed revision control system it is aimed at speed,[9] data integrity,[10] and support for distributed, non-linear workflows.[11]

Git was created by Linus Torvalds in 2005 for development of the Linux kernel, with other kernel developers contributing to its initial development.

most other distributed version control systems, and unlike most client–server systems, every Git directory on every computer is a full-fledged repository with complete history and full version tracking abilities, independent of network access or a central server.[13]

Linus Torvalds wanted a distributed system that he could use like BitKeeper, but none of the available free systems met his needs, especially for performance. Torvalds cited an example of a source-control management system needing 30 seconds to apply a patch and update all associated metadata, and noted that this would not scale to the needs of Linux kernel development, where syncing with fellow maintainers could require 250 such actions at once. For his design criteria, he specified that patching should take no more than three seconds,

The university acquired a UNIX source license from AT&T. Students of the university started to modify and improve the AT&T Unix and called this modified version "Berkeley Unix" or "BSD", implementing features such as TCP/IP, virtual memory and the Unix File System. The BSD project was founded in 1976 by Bill Joy. But since BSD contained code from AT&T, Unix, all recipients had to get a license from AT&T first in order to use BSD.[9]

In June 1989, "Networking Release 1" or simply Net-1 – the first public version of BSD – was released. After releasing Net-1, Keith Bostic, a developer of BSD, suggested replacing all AT&T code with freely-redistributable code under the original BSD license. Work on replacing AT&T code began and, after 18 months, much of the AT&T code was replaced. However, six files containing AT&T code remained in the kernel. The BSD developers decided to release the "Networking Release 2" (Net-2) without those six files. Net-2 was released in 1991.[9]

During its lifetime, several competing products were released for the x86 platform,[10] and MS-DOS went through eight versions, until development ceased in 2000.[11][dead link] Initially MS-DOS was targeted at Intel 8086 processors running on computer hardware using floppy disks to store and access not only the operating system, but application software and user data as well. Progressive version releases delivered support for other mass storage media in ever greater sizes and formats, along with added feature support for newer processors and rapidly evolving computer architectures. Ultimately it was the key product in Microsoft's growth from a programming languages company to a diverse software development firm, providing the company with essential revenue and marketing resources. It was also the underlying basic operating system on which early versions of Windows ran as a GUI. It is a flexible operating system, and consumes negligible installation space.

MS-DOS was a renamed form of 86-DOS[12] – owned by Seattle Computer Products, written by Tim Paterson. Development of 86-DOS took only six weeks, as it was basically a clone of Digital Research's CP/M (for 8080/Z80 processors), ported to run on 8086 processors and with two notable differences compared to CP/M; an improved disk sector buffering logic and the introduction of FAT12 instead of the CP/M filesystem. This first version was shipped in August 1980.[5] Microsoft, which needed an operating system for the IBM Personal Computer[7][8] hired Tim Paterson in May 1981 and bought 86-DOS 1.10 for $75,000 in July of the same year. Microsoft kept the version number, but renamed it MS-DOS. They also licensed MS-DOS 1.10/1.14 to IBM, who, in August 1981, offered it as PC DOS 1.0 as one of three operating systems[13] for the IBM 5150, or the IBM PC.[5]