Windows XP is a personal computer operating system produced by Microsoft as part of the Windows NT family of operating systems. It was released to manufacturing on August 24, 2001, broadly released for retail sale on October 25, 2001. Development of Windows XP began in the late 1990s as "Neptune", an operating system built on the Windows NT kernel, intended for mainstream consumer use. An updated version of Windows 2000 was originally planned for the business market; as such, Windows XP was the first consumer edition of Windows not to be based on MS-DOS. Upon its release, Windows XP received positive reviews, with critics noting increased performance and stability, a more intuitive user interface, improved hardware support, expanded multimedia capabilities. However, some industry reviewers were concerned by the new licensing model and product activation system. Extended support for Windows XP ended on April 8, 2014, after which the operating system ceased receiving further support or security updates to most users.
As of March 2019, 1.75% of Windows PCs run Windows XP, the OS is still most popular in some countries with up to 38% of the Windows share. In the late 1990s, initial development of what would become Windows XP was focused on two individual products. However, the projects proved to be too ambitious. In January 2000, shortly prior to the official release of Windows 2000, technology writer Paul Thurrott reported that Microsoft had shelved both Neptune and Odyssey in favor of a new product codenamed "Whistler", after Whistler, British Columbia, as many Microsoft employees skied at the Whistler-Blackcomb ski resort; the goal of Whistler was to unify both the consumer and business-oriented Windows lines under a single, Windows NT platform: Thurrott stated that Neptune had become "a black hole when all the features that were cut from were re-tagged as Neptune features. And since Neptune and Odyssey would be based on the same code-base anyway, it made sense to combine them into a single project". At PDC on July 13, 2000, Microsoft announced that Whistler would be released during the second half of 2001, unveiled the first preview build, 2250.
The build notably introduced an early version of Windows XP's visual styles system. Microsoft released the first beta build of Whistler, build 2296, on October 31, 2000. Subsequent builds introduced features that users of the release version of Windows XP would recognise, such as Internet Explorer 6.0, the Microsoft Product Activation system and the Bliss desktop background. On February 5, 2001, Microsoft announced that Whistler would be known as Windows XP, where XP stands for "eXPerience". In June 2001, Microsoft indicated that it was planning to, in conjunction with Intel and other PC makers, spend at least 1 billion US dollars on marketing and promoting Windows XP; the theme of the campaign, "Yes You Can", was designed to emphasize the platform's overall capabilities. Microsoft had planned to use the slogan "Prepare to Fly", but it was replaced due to sensitivity issues in the wake of the September 11 attacks. On August 24, 2001, Windows XP build. During a ceremonial media event at Microsoft Redmond Campus, copies of the RTM build were given to representatives of several major PC manufacturers in briefcases, who flew off on decorated helicopters.
While PC manufacturers would be able to release devices running XP beginning on September 24, 2001, XP was expected to reach general, retail availability on October 25, 2001. On the same day, Microsoft announced the final retail pricing of XP's two main editions, "Home" and "Professional". While retaining some similarities to previous versions, Windows XP's interface was overhauled with a new visual appearance, with an increased use of alpha compositing effects, drop shadows, "visual styles", which changed the appearance of the operating system; the number of effects enabled are determined by the operating system based on the computer's processing power, can be enabled or disabled on a case-by-case basis. XP added ClearType, a new subpixel rendering system designed to improve the appearance of fonts on liquid-crystal displays. A new set of system icons was introduced; the default wallpaper, Bliss, is a photo of a landscape in the Napa Valley outside Napa, with rolling green hills and a blue sky with stratocumulus and cirrus clouds.
The Start menu received its first major overhaul in XP, switching to a two-column layout with the ability to list and display used applications opened documents, the traditional cascading "All Programs" menu. The taskbar can now group windows opened by a single application into one taskbar button, with a popup menu listing the individual windows; the notification area hides "inactive" icons by default. A "common tasks" list was added, Windows Explorer's sidebar was updated to use a new task-based design with lists of common actions. Fast user switching allows additional users to log into a Windows XP machine without existing users having to close their programs and loggin
History of Firefox
Mozilla Firefox was created by Dave Hyatt and Blake Ross as an experimental branch of the Mozilla browser. Firefox 1.0 was released on November 9, 2004, Firefox 1.5 was released on November 29, 2005, version 2.0 was released on October 24, 2006. Firefox 3.0 was released on June 17, 2008, with Firefox 3.5 and Firefox 3.6 released on June 30, 2009 and January 21, 2010, respectively. Firefox 4 was released on March 22, 2011. Since version 5.0, a rapid release cycle was put into effect, resulting in a new major version release every six weeks on Tuesday. The latest version, Firefox 66.0, was released on March 19, 2019. The project that became Firefox began as an experimental branch of the Mozilla Suite called m/b. After it was sufficiently developed, binaries for public testing appeared in September 2002 under the name Phoenix; this name carried the implication of the mythical firebird that rose triumphantly from the ashes of its dead predecessor, in this case Netscape Navigator which lost the "First browser war" to Microsoft's Internet Explorer.
The name Mozilla began as the internal codename for the original 1994 Netscape Navigator browser aiming to displace NCSA Mosaic as the world's most popular web browser. The name for this would-be "Mosaic killer" was meant to evoke the building-crushing Godzilla; the name Mozilla was revived as the 1998 open sourcing spinoff organization from Netscape. The name Phoenix remained until April 14, 2003, when it was changed because of a trademark dispute with the BIOS manufacturer Phoenix Technologies; the new name, met with mixed reactions as the Firebird database server carried the name. In response, the Mozilla Foundation stated that the browser should always bear the name Mozilla Firebird to avoid confusion with the database software. Due to continuing pressure from the Firebird community, on February 9, 2004 the project was renamed again to Mozilla Firefox; the name "Firefox" was chosen for its similarity to "Firebird", its uniqueness in the computing industry. To ensure that no further name changes would be necessary, the Mozilla Foundation began the process of registering Firefox as a trademark with the United States Patent and Trademark Office in December 2003.
This trademark process led to a delay of several months in the release of Firefox 0.8 when the foundation discovered that Firefox had been registered as a trademark in the UK for Charlton Company software. The situation was resolved when the foundation was given a license to use Charlton's European trademark. Hyatt, Ross and Chanial developed their browser to combat the perceived software bloat of the Mozilla Suite, which integrated features such as IRC, news, WYSIWYG HTML editing into one internet suite. Firefox retains the cross-platform nature of the original Mozilla browser, using the XUL user interface markup language; the use of XUL makes it possible to extend the browser's capabilities through the use of extensions and themes. The development and installation processes of these add-ons raised security concerns, with the release of Firefox 0.9, the Mozilla Foundation opened a Mozilla Update website containing "approved" themes and extensions. The use of XUL sets Firefox apart from other browsers, including other projects based on Mozilla's Gecko layout engine and most other browsers, which use interfaces native to their respective platforms.
Many of these projects started before Firefox, served as inspiration. On February 5, 2004, AMS, a business and IT consulting company, categorized Mozilla Firefox as a "Tier 1" open-source product, considering it technically strong and risk-free. May 15, 2003 was the publication day of Phoenix 0.1. October 26, 2003 was the publication day of Firebird 0.7. Firefox 1.0 was released on November 9, 2004. The launch of version 1.0 was accompanied by "a respectable amount of pre-launch fervor" including a fan-organized campaign to run a full-page ad in The New York Times. Although the Mozilla Foundation had intended to make the Mozilla Suite obsolete and replace it with Firefox, the Foundation continued to maintain the suite until April 12, 2006 because it had many corporate users and was bundled with other software; the Mozilla community continues to release new versions of the suite, using the product name SeaMonkey to avoid confusion with the original Mozilla Suite. Firefox 1.5 was released on November 30, 2005.
It was planned to have a version 1.1 at an earlier date as the new Firefox version after 1.0, with development on a version in a separate development branch, but during 2005 both branches and their feature sets were merged, resulting in an official release date between the original dates planned for both versions. Version 1.5 implemented a new Mac-like options interface, the subject of much criticism from Microsoft Windows and Linux users, with a "Sanitize" action to allow someone to clear their privacy-related information without manually clicking the "Clear All" button. In Firefox 1.5, a user could clear all privacy-related settings by exiting the browser or using a keyboard shortcut, depending on their settings. Moreover, the software update system was improved. There were improvements in the extension management system, with a number of new developer features. In addition, Firefox 1.5 had preliminary SVG 1.1 support. Behind the screens, the new v
In telecommunications, broadband is wide bandwidth data transmission which transports multiple signals and traffic types. The medium can be optical fiber, radio or twisted pair. In the context of Internet access, broadband is used to mean any high-speed Internet access, always on and faster than dial-up access over traditional analog or ISDN PSTN services. Different criteria for "broad" have been applied at different times, its origin is in physics and radio systems engineering, where it had been used with a meaning similar to "wideband". With the advent of digital telecommunications, the term was used for transmission over multiple channels. Whereas a passband signal is modulated so that it occupies higher frequencies, it is still occupying a single channel; the key difference is that what is considered a broadband signal in this sense is a signal that occupies multiple passbands, thus allowing for much higher throughput over a single medium but with additional complexity in the transmitter/receiver circuitry.
The term became popularized through the 1990s as a marketing term for Internet access, faster than dialup access, the original Internet access technology, limited to a maximum bandwidth of 56 kbit/s. This meaning is only distantly related to its original technical meaning. In telecommunications, a broadband signalling method is one. "Broadband" is a relative term, understood according to its context. The wider the bandwidth of a channel, the greater the data-carrying capacity, given the same channel quality. In radio, for example, a narrow band will carry Morse code, a broader band will carry speech, a still broader band will carry music without losing the high audio frequencies required for realistic sound reproduction; this broad band is divided into channels or "frequency bins" using passband techniques to allow frequency-division multiplexing instead of sending a higher-quality signal. In data communications, a 56k modem will transmit a data rate of 56 kilobits per second over a 4-kilohertz-wide telephone line.
In the late 1980s, the Broadband Integrated Services Digital Network used the term to refer to a broad range of bit rates, independent of physical modulation details. The various forms of digital subscriber line services are broadband in the sense that digital information is sent over multiple channels; each channel is at higher frequency than the baseband voice channel, so it can support plain old telephone service on a single pair of wires at the same time. However, when that same line is converted to a non-loaded twisted-pair wire, it becomes hundreds of kilohertz wide and can carry up to 100 megabits per second using very-high-bit-rate digital subscriber line techniques. Many computer networks use a simple line code to transmit one type of signal using a medium's full bandwidth using its baseband. Most versions of the popular Ethernet family are given names such as the original 1980s 10BASE5 to indicate this. Networks that use cable modems on standard cable television infrastructure are called broadband to indicate the wide range of frequencies that can include multiple data users as well as traditional television channels on the same cable.
Broadband systems use a different radio frequency modulated by the data signal for each band. The total bandwidth of the medium is larger than the bandwidth of any channel; the 10BROAD36 broadband variant of Ethernet was standardized by 1985, but was not commercially successful. The DOCSIS standard became available to consumers in the late 1990s, to provide Internet access to cable television residential customers. Matters were further confused by the fact that the 10PASS-TS standard for Ethernet ratified in 2008 used DSL technology, both cable and DSL modems have Ethernet connectors on them. A television antenna may be described as "broadband" because it is capable of receiving a wide range of channels, while a single-frequency or Lo-VHF antenna is "narrowband" since it receives only 1 to 5 channels; the U. S. federal standard FS-1037C defines "broadband" as a synonym for wideband. "Broadband" in analog video distribution is traditionally used to refer to systems such as cable television, where the individual channels are modulated on carriers at fixed frequencies.
In this context, baseband is the term's antonym, referring to a single channel of analog video in composite form with separate baseband audio. The act of demodulating converts broadband video to baseband video. Fiber optic allows the signal to be transmitted farther without being repeated. Cable companies use a hybrid system using fiber to transmit the signal to neighborhoods and changes the signal from light to radio frequency to be transmitted over coaxial cable to homes. Doing so reduces the use of having multiple head ends. A head end gathers all the information from the local cable networks and movie channels and feeds the information into the system. However, "broadband video" in the context of streaming Internet video has come to mean video files that have bit-rates high enough to require broadband Internet access for viewing. "Broadband video" is sometimes used to describe IPTV Video on demand. Power lines have been used for various types of data communication. Although some systems for remote control are based on narrowband signaling, modern high-speed systems use broadband signaling to achieve high data rates.
One example is the ITU-T G.hn standard, which provides a
Microsoft Windows is a group of several graphical operating system families, all of which are developed and sold by Microsoft. Each family caters to a certain sector of the computing industry. Active Windows families include Windows Embedded. Defunct Windows families include Windows Mobile and Windows Phone. Microsoft introduced an operating environment named Windows on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces. Microsoft Windows came to dominate the world's personal computer market with over 90% market share, overtaking Mac OS, introduced in 1984. Apple came to see Windows as an unfair encroachment on their innovation in GUI development as implemented on products such as the Lisa and Macintosh. On PCs, Windows is still the most popular operating system. However, in 2014, Microsoft admitted losing the majority of the overall operating system market to Android, because of the massive growth in sales of Android smartphones.
In 2014, the number of Windows devices sold was less than 25 %. This comparison however may not be relevant, as the two operating systems traditionally target different platforms. Still, numbers for server use of Windows show one third market share, similar to that for end user use; as of October 2018, the most recent version of Windows for PCs, tablets and embedded devices is Windows 10. The most recent versions for server computers is Windows Server 2019. A specialized version of Windows runs on the Xbox One video game console. Microsoft, the developer of Windows, has registered several trademarks, each of which denote a family of Windows operating systems that target a specific sector of the computing industry; as of 2014, the following Windows families are being developed: Windows NT: Started as a family of operating systems with Windows NT 3.1, an operating system for server computers and workstations. It now consists of three operating system subfamilies that are released at the same time and share the same kernel: Windows: The operating system for mainstream personal computers and smartphones.
The latest version is Windows 10. The main competitor of this family is macOS by Apple for personal computers and Android for mobile devices. Windows Server: The operating system for server computers; the latest version is Windows Server 2019. Unlike its client sibling, it has adopted a strong naming scheme; the main competitor of this family is Linux. Windows PE: A lightweight version of its Windows sibling, meant to operate as a live operating system, used for installing Windows on bare-metal computers, recovery or troubleshooting purposes; the latest version is Windows PE 10. Windows IoT: Initially, Microsoft developed Windows CE as a general-purpose operating system for every device, too resource-limited to be called a full-fledged computer. However, Windows CE was renamed Windows Embedded Compact and was folded under Windows Compact trademark which consists of Windows Embedded Industry, Windows Embedded Professional, Windows Embedded Standard, Windows Embedded Handheld and Windows Embedded Automotive.
The following Windows families are no longer being developed: Windows 9x: An operating system that targeted consumers market. Discontinued because of suboptimal performance. Microsoft now caters to the consumer market with Windows NT. Windows Mobile: The predecessor to Windows Phone, it was a mobile phone operating system; the first version was called Pocket PC 2000. The last version is Windows Mobile 6.5. Windows Phone: An operating system sold only to manufacturers of smartphones; the first version was Windows Phone 7, followed by Windows Phone 8, the last version Windows Phone 8.1. It was succeeded by Windows 10 Mobile; the term Windows collectively describes any or all of several generations of Microsoft operating system products. These products are categorized as follows: The history of Windows dates back to 1981, when Microsoft started work on a program called "Interface Manager", it was announced in November 1983 under the name "Windows", but Windows 1.0 was not released until November 1985.
Windows 1.0 was to achieved little popularity. Windows 1.0 is not a complete operating system. The shell of Windows 1.0 is a program known as the MS-DOS Executive. Components included Calculator, Cardfile, Clipboard viewer, Control Panel, Paint, Reversi and Write. Windows 1.0 does not allow overlapping windows. Instead all windows are tiled. Only modal dialog boxes may appear over other windows. Microsoft sold as included Windows Development libraries with the C development environment, which included numerous windows samples. Windows 2.0 was released in December 1987, was more popular than its predecessor. It features several improvements to the user memory management. Windows 2.03 changed the OS from tiled windows to overlapping windows. The result of this change led to Apple Computer filing a suit against Microsoft alleging infringement on Apple's copyrights. Windows 2.0
Mozilla Firefox is a free and open-source web browser developed by The Mozilla Foundation and its subsidiary, Mozilla Corporation. Firefox is available for Microsoft Windows, macOS, Linux, BSD, illumos and Solaris operating systems, its sibling, Firefox for Android, is available. Firefox uses the Gecko layout engine to render web pages, which implements current and anticipated web standards. In 2017, Firefox began incorporating new technology under the code name Quantum to promote parallelism and a more intuitive user interface. An additional version, Firefox for iOS, was released on November 12, 2015. Due to platform restrictions, it uses the WebKit layout engine instead of Gecko, as with all other iOS web browsers. Firefox was created in 2002 under the codename "Phoenix" by the Mozilla community members who desired a standalone browser, rather than the Mozilla Application Suite bundle. During its beta phase, Firefox proved to be popular with its testers and was praised for its speed and add-ons compared to Microsoft's then-dominant Internet Explorer 6.
Firefox was released on November 9, 2004, challenged Internet Explorer's dominance with 60 million downloads within nine months. Firefox is the spiritual successor of Netscape Navigator, as the Mozilla community was created by Netscape in 1998 before their acquisition by AOL. Firefox usage grew to a peak of 32% at the end of 2009, with version 3.5 overtaking Internet Explorer 7, although not Internet Explorer as a whole. Usage declined in competition with Google Chrome; as of January 2019, Firefox has 9.5% usage share as a "desktop" browser, according to StatCounter, making it the second-most popular such web browser. Firefox is still the most popular desktop browser in a few countries including Cuba and Eritrea with 72.26% and 83.28% of the market share, respectively. According to Mozilla, in December 2014, there were half a billion Firefox users around the world; the project began as an experimental branch of the Mozilla project by Dave Hyatt, Joe Hewitt, Blake Ross. They believed the commercial requirements of Netscape's sponsorship and developer-driven feature creep compromised the utility of the Mozilla browser.
To combat what they saw as the Mozilla Suite's software bloat, they created a stand-alone browser, with which they intended to replace the Mozilla Suite. On April 3, 2003, the Mozilla Organization announced that they planned to change their focus from the Mozilla Suite to Firefox and Thunderbird; the community-driven SeaMonkey was formed and replaced the Mozilla Application Suite in 2005. The Firefox project has undergone several name changes, it was titled Phoenix, which carried the implication of the mythical firebird that rose triumphantly from the ashes of its dead predecessor, in this case from the "ashes" of Netscape Navigator after it had been killed off by Microsoft Internet Explorer in the "First Browser War". Phoenix was renamed due to trademark issues with Phoenix Technologies. In response, the Mozilla Foundation stated that the browser would always bear the name Mozilla Firebird to avoid confusion. After further pressure, on February 9, 2004, Mozilla Firebird became Mozilla Firefox.
The name Firefox was said to be derived from a nickname of the red panda, which became the mascot for the newly named project. For the abbreviation of Firefox, Mozilla prefers Fx or fx, though it is abbreviated as FF; the Firefox project went through many versions before version 1.0 was released on November 9, 2004. In 2016, Mozilla announced a project known as Quantum, which sought to improve Firefox's Gecko engine and other components to improve Firefox's performance, modernize its architecture, transition the browser to a multi-process model; these improvements came in the wake of decreasing market share to Google Chrome, as well as concerns that its performance was lapsing in comparison. Despite its improvements, these changes required existing add-ons for Firefox to be made incompatible with newer versions, in favor of a new extension system, designed to be similar to Chrome and other recent browsers. Firefox 57, released in November 2017, was the first version to contain enhancements from Quantum, has thus been named Firefox Quantum.
Firefox supported add-ons using the XUL and XPCOM APIs, which allowed them to directly access and manipulate much of the browser's internal functionality. As they are not compatible with its m
A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. Data sent through the internet, such as a web page or email, is in the form of data packets. A packet is forwarded from one router to another router through the networks that constitute an internetwork until it reaches its destination node. A router is connected to two or more data lines from different networks; when a data packet comes in on one of the lines, the router reads the network address information in the packet to determine the ultimate destination. Using information in its routing table or routing policy, it directs the packet to the next network on its journey; the most familiar type of routers are home and small office routers that forward IP packets between the home computers and the Internet. An example of a router would be the owner's cable or DSL router, which connects to the Internet through an Internet service provider. More sophisticated routers, such as enterprise routers, connect large business or ISP networks up to the powerful core routers that forward data at high speed along the optical fiber lines of the Internet backbone.
Though routers are dedicated hardware devices, software-based routers exist. When multiple routers are used in interconnected networks, the routers can exchange information about destination addresses using a routing protocol; each router builds up a routing table listing the preferred routes between any two systems on the interconnected networks. A router has two types of network element components organized onto separate planes: Control plane: A router maintains a routing table that lists which route should be used to forward a data packet, through which physical interface connection, it does this using internal preconfigured directives, called static routes, or by learning routes dynamically using a routing protocol. Static and dynamic routes are stored in the routing table; the control-plane logic strips non-essential directives from the table and builds a forwarding information base to be used by the forwarding plane. Forwarding plane: The router forwards data packets between incoming and outgoing interface connections.
It forwards them to the correct network type using information that the packet header contains matched to entries in the FIB supplied by the control plane. A router may have interfaces for different types of physical layer connections, such as copper cables, fiber optic, or wireless transmission, it can support different network layer transmission standards. Each network interface is used to enable data packets to be forwarded from one transmission system to another. Routers may be used to connect two or more logical groups of computer devices known as subnets, each with a different network prefix. Routers may provide connectivity within enterprises, between enterprises and the Internet, or between internet service providers' networks; the largest routers may be used in large enterprise networks. Smaller routers provide connectivity for typical home and office networks. All sizes of routers may be found inside enterprises; the most powerful routers are found in ISPs, academic and research facilities.
Large businesses may need more powerful routers to cope with ever-increasing demands of intranet data traffic. A hierarchical internetworking model for interconnecting routers in large networks is in common use. Access routers, including small office/home office models, are located at home and customer sites such as branch offices that do not need hierarchical routing of their own, they are optimized for low cost. Some SOHO routers are capable of running alternative free Linux-based firmware like Tomato, OpenWrt or DD-WRT. Distribution routers aggregate traffic from multiple access routers. Distribution routers are responsible for enforcing quality of service across a wide area network, so they may have considerable memory installed, multiple WAN interface connections, substantial onboard data processing routines, they may provide connectivity to groups of file servers or other external networks. In enterprises, a core router may provide a collapsed backbone interconnecting the distribution tier routers from multiple buildings of a campus, or large enterprise locations.
They lack some of the features of edge routers. External networks must be considered as part of the overall security strategy of the local network. A router may include a firewall, VPN handling, other security functions, or these may be handled by separate devices. Routers commonly perform network address translation which restricts connections initiated from external connections but is not recognised as a security feature by all experts.. Some experts argue that open source routers are more secure and reliable than closed source routers because open source routers allow mistakes to be found and corrected. Routers are often distinguished on the basis of the network in which they operate. A router in a local area network of a single organisation is called an interior router. A router, operated in the Internet backbone is described as exterior router. While a router that connects a LAN with the Internet or a wide area network is called a border router, or gateway router. Routers intended for ISP and major enterprise connectivity exchange routing information using the Border Gateway Protocol.
RFC 4098 standard defines the types of BGP routers according to their functions: Edge router: Also called a provider edge router, is placed at the edge of an ISP network. The router uses External BGP to EBGP
Linux is a family of free and open-source software operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is packaged in a Linux distribution. Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy. Popular Linux distributions include Debian and Ubuntu. Commercial distributions include SUSE Linux Enterprise Server. Desktop Linux distributions include a windowing system such as X11 or Wayland, a desktop environment such as GNOME or KDE Plasma. Distributions intended for servers may omit graphics altogether, include a solution stack such as LAMP; because Linux is redistributable, anyone may create a distribution for any purpose. Linux was developed for personal computers based on the Intel x86 architecture, but has since been ported to more platforms than any other operating system.
Linux is the leading operating system on servers and other big iron systems such as mainframe computers, the only OS used on TOP500 supercomputers. It is used by around 2.3 percent of desktop computers. The Chromebook, which runs the Linux kernel-based Chrome OS, dominates the US K–12 education market and represents nearly 20 percent of sub-$300 notebook sales in the US. Linux runs on embedded systems, i.e. devices whose operating system is built into the firmware and is tailored to the system. This includes routers, automation controls, digital video recorders, video game consoles, smartwatches. Many smartphones and tablet computers run other Linux derivatives; because of the dominance of Android on smartphones, Linux has the largest installed base of all general-purpose operating systems. Linux is one of the most prominent examples of open-source software collaboration; the source code may be used and distributed—commercially or non-commercially—by anyone under the terms of its respective licenses, such as the GNU General Public License.
The Unix operating system was conceived and implemented in 1969, at AT&T's Bell Laboratories in the United States by Ken Thompson, Dennis Ritchie, Douglas McIlroy, Joe Ossanna. First released in 1971, Unix was written in assembly language, as was common practice at the time. In a key pioneering approach in 1973, it was rewritten in the C programming language by Dennis Ritchie; the availability of a high-level language implementation of Unix made its porting to different computer platforms easier. Due to an earlier antitrust case forbidding it from entering the computer business, AT&T was required to license the operating system's source code to anyone who asked; as a result, Unix grew and became adopted by academic institutions and businesses. In 1984, AT&T divested itself of Bell Labs; the GNU Project, started in 1983 by Richard Stallman, had the goal of creating a "complete Unix-compatible software system" composed of free software. Work began in 1984. In 1985, Stallman started the Free Software Foundation and wrote the GNU General Public License in 1989.
By the early 1990s, many of the programs required in an operating system were completed, although low-level elements such as device drivers and the kernel, called GNU/Hurd, were stalled and incomplete. Linus Torvalds has stated that if the GNU kernel had been available at the time, he would not have decided to write his own. Although not released until 1992, due to legal complications, development of 386BSD, from which NetBSD, OpenBSD and FreeBSD descended, predated that of Linux. Torvalds has stated that if 386BSD had been available at the time, he would not have created Linux. MINIX was created by Andrew S. Tanenbaum, a computer science professor, released in 1987 as a minimal Unix-like operating system targeted at students and others who wanted to learn the operating system principles. Although the complete source code of MINIX was available, the licensing terms prevented it from being free software until the licensing changed in April 2000. In 1991, while attending the University of Helsinki, Torvalds became curious about operating systems.
Frustrated by the licensing of MINIX, which at the time limited it to educational use only, he began to work on his own operating system kernel, which became the Linux kernel. Torvalds began the development of the Linux kernel on MINIX and applications written for MINIX were used on Linux. Linux matured and further Linux kernel development took place on Linux systems. GNU applications replaced all MINIX components, because it was advantageous to use the available code from the GNU Project with the fledgling operating system. Torvalds initiated a switch from his original license, which prohibited commercial redistribution, to the GNU GPL. Developers worked to integrate GNU components with the Linux kernel, making a functional and free operating system. Linus Torvalds had wanted to call his invention "Freax", a portmant