Ubuntu

Ubuntu is a computer operating system based on Debian GNU/Linux. Ubuntu's goals include providing an up-to-date, stable operating system for the average user, with a strong focus on usability and ease of installation. Ubuntu has been rated as the most popular Linux distribution for the desktop, claiming approximately 30% of desktop Linux installations in 2007.
Ubuntu is composed of free and open source software distributed under various licenses, especially the GNU General Public License (GPL) so that users are free to run, copy, distribute, study, change and improve the software. Ubuntu is sponsored by the UK based company Canonical Ltd., owned by South African entrepreneur Mark Shuttleworth. Instead of selling Ubuntu for profit, Canonical creates revenue by selling technical support. By keeping Ubuntu free and open source, Canonical is able to take advantage of the talents of outside developers in Ubuntu's constituent components without developing the entire operating system itself.
Canonical endorses and provides support for four additional Ubuntu-based distributions: Kubuntu and Xubuntu, Edubuntu, a subproject and add-on for Ubuntu, designed for school environments and home use; and Ubuntu JeOS (pronounced "Juice"), a stripped-down version of Ubuntu, optimized for virtual appliances.
Canonical releases new versions of Ubuntu every six months and supports Ubuntu for eighteen months by submitting security fixes, patches to critical bugs and including minor updates to programs. LTS (Long Term Support) releases, which occur every two years, are supported for three years on the desktop and five years for servers. The current version of Ubuntu, Intrepid Ibex, was released on October 30, 2008, and the upcoming version, Jaunty Jackalope, will be released in April, 2009. The version after Jaunty will be Karmic Koala, which will possess several advanced features like Eucalyptus.
History and development process
Ubuntu was initially forked from the Debian project's code base. The aim was to release a new version of Ubuntu every six months, resulting in a more frequently updated system. Ubuntu's first release was on October 20, 2004. The name Ubuntu, pronounced IPA: [uːˈbuːntuː] in English, comes from the Zulu word "ubuntu" ([ùɓúntú]), translated as "humanity to others", describing the ubuntu philosophy: "I am what I am because of who we all are", a positive aspect of community.
New releases of Ubuntu coincide a month after GNOME releases. In contrast to previous general-purpose forks of Debian — such as MEPIS, Xandros, Linspire, Progeny and Libranet, many of which relied on proprietary and closed source add-ons as part of their business model — Ubuntu has stayed closer to Debian's philosophy and uses free (libre) software, making an exception only for some proprietary hardware drivers.
Ubuntu packages are based on packages from Debian's unstable branch: both distributions use Debian's deb package format and package management tools, APT and Synaptic, although Debian and Ubuntu packages are not necessarily binary compatible with each other, and may need to be rebuilt from source. Ubuntu cooperates with Debian — to some extent pushing changes back to Debian, although there has been criticism that this doesn't happen often enough. Many Ubuntu developers are also maintainers of key packages within Debian. However, Ian Murdock, the founder of Debian, expressed concern about Ubuntu packages diverging too far from Debian Sarge to remain compatible.
Before release, packages are imported from Debian Unstable continuously and merged with Ubuntu-specific modifications. A month before release, imports are frozen, and soon after a feature freeze is instated, which allows for packages to work on ensuring that the current software works well, rather than supporting the moving target that is Unstable.
Ubuntu is currently funded by Canonical Ltd. On July 8, 2005, Mark Shuttleworth and Canonical Ltd announced the creation of the Ubuntu Foundation and provided an initial funding of US$10 million. The purpose of the foundation is to ensure the support and development for all future versions of Ubuntu. Mark Shuttleworth describes the foundation as an emergency fund in case Canonical's involvement ends.
The Ubuntu logo and typography has remained the same since that first release. The hand-drawn, lowercase OpenType font used is called Ubuntu-Title and was created by Andy Fitzsimon. The font is distributed under the terms of the GNU Lesser General Public License (LGPL) and use with logos derived from the Ubuntu logo is encouraged.[17] The font is available as a package for Ubuntu.
Ubuntu 8.04, released on April 24, 2008, is the current Long Term Support (LTS) release. Canonical has released previous LTS versions every two years, and has committed to releasing the next LTS version in 2010, two years after 8.04.Meanwhile, the current standard-support period release, Ubuntu 8.10 (Intrepid Ibex), was released on October 30, 2008.
Feature
Installing and removing software in Ubuntu
Ubuntu focuses on usability, including the widespread use of the sudo tool for administrative tasks. The Ubiquity installer allows installing Ubuntu to the hard disk from within the Live CD environment without the need for restarting the computer prior to installation. Ubuntu also emphasizes accessibility and internationalization, to reach as many people as possible. Beginning with 5.04, UTF-8 became the default character encoding, which allows for support of a variety of non-Roman scripts. The default appearance of the user interface in the current version is called Human and is characterized by shades of brown and orange.
The most recent version of Ubuntu comes installed with a wide range of software including OpenOffice, Firefox, Pidgin, Transmission, and GIMP. Several lightweight card, puzzle, and board games are pre-installed, such as Sudoku and chess. Ubuntu has all networking ports closed by default for added security; its firewall offers fine-grained control of incoming and outgoing connections. GNOME 2.22—the default desktop environment of Ubuntu 8.04—offers support for 46 languages.[24] There are several ways to install Ubuntu, outlined below.
Live CD
Installation of Ubuntu is generally performed with the Live CD, which presents the system to the user as it would run off the hard drive (albeit with a performance hit from loading applications off the CD). This is particularly useful in testing for hardware compatibility and driver support. The CD also contains the Ubiquity installer, which guides the user through the permanent installation process. CD images of all current and past versions are available for download at the Ubuntu web site. Installing from the CD requires a minimum of 256 MB RAM. Users can download a disk image of the CD which can then be written to a physical medium, or run from a hard drive via UNetbootin.
Canonical offers Ubuntu, Kubuntu and Edubuntu installation CDs at no cost, including paid postage for destinations in most countries around the world, via a service called ShipIt. Xubuntu is not offered due to lack of demand. After a request for CDs is made and approved, disks are sent via post. Delivery is estimated at six to ten weeks.
A Microsoft Windows migration tool was introduced in April 2007, when Ubuntu 7.04 was released. The new migration tool, called Migration Assistant, imports Windows users' bookmarks, desktop background (wallpaper), and various settings for immediate use in the Ubuntu installation.
Ubuntu and Kubuntu (from release 8.10 onwards) can be booted and run from a USB Flash drive (as long as the BIOS supports booting from USB), with the option of saving settings to the flashdrive or running without saving settings. This allows a portable installation that can be run on any PC which is capable of booting from a USB drive.
Wubi, which is included on the Live CD, allows the distribution to be installed on a virtual loop device. This requires no partitioning of a user's hard drive, allowing them to install Ubuntu to a file on their Windows drive. Wubi also makes use of the Migration Assistant to import users' settings. Wubi was initially developed as an independent project, and as such versions 7.04 and 7.10 were released separately from Ubuntu. Wubi was later merged with Ubuntu, and can be found in the Ubuntu Live CD as of the 8.04 release. A related program, USB creator, makes it possible to install Ubuntu on a USB drive without the need of burning a disc.
Remastering
See also: List of remastering software
Various programs exist to produce customised remasters of the Ubuntu Live CD, which some refer to as a "Custom Spin", such as remastersys and Reconstructor.
Package classification and support
Ubuntu divides all software into four domains to reflect differences in licensing and the degree of support available.[35] They are as follows:
free software
non-free software

supported Main Restricted
unsupported Universe Multiverse
Free software here includes only software that meets the Ubuntu licensing requirements, which roughly correspond to the Debian Free Software Guidelines. There is one exception for the Main category, however — it contains firmware and fonts which are not allowed to be modified, but are included because their distribution is otherwise unencumbered.
Non-free software is usually unsupported (Multiverse), but some exceptions (Restricted) are made for very important non-free software. Supported non-free software includes device drivers that can be used to run Ubuntu on some current hardware, such as binary-only graphics card drivers. The level of support in the Restricted category is more limited than that of Main, since the developers may not have access to the source code. It is intended that Main and Restricted should contain all software needed for a general-use Linux system. Alternative programs for the same tasks and programs for specialized applications are placed in the Universe and Multiverse categories.
In addition to the above, in which the software does not receive new features after an initial release, Ubuntu Backports is an officially recognized project to backport newer software from later versions of Ubuntu. The repository is not comprehensive; it consists primarily of user-requested packages, which are approved if they meet quality guidelines. Backports receives no support at all from Canonical, and is entirely community-maintained.
Availability of third-party software
See also: Linux distribution#Proprietary software, Medibuntu, Getdeb, and Ubuntu extras remix
Ubuntu has a certification system for third party software. Some third-party software that does not limit distribution is included in Ubuntu's multiverse component. The package ubuntu-restricted-extras additionally contains software that may be legally restricted, including support for MP3 and DVD playback, Microsoft TrueType core fonts, Sun's Java runtime environment, Adobe's Flash Player plugin, many common audio/video codecs, and unrar, an unarchiver for files compressed in the RAR file format.
Additionally, several third party application suites are available for purchase through the Canonical web-based store, including software for DVD playback and media codecs.

www.wikipedia.org