Ubuntu is a free and open-source Linux distribution based on Debian. Ubuntu is released in three editions: Desktop and Core. Ubuntu is a popular operating system for cloud computing, with support for OpenStack. Ubuntu is released every six months, with long-term support releases every two years; the latest release is 18.10, the most recent long-term support release is 18.04 LTS, supported until 2028. Ubuntu is developed by the community under a meritocratic governance model. Canonical provides security updates and support for each Ubuntu release, starting from the release date and until the release reaches its designated end-of-life date. Canonical generates revenue through the sale of premium services related to Ubuntu. Ubuntu is named after the African philosophy of ubuntu, which Canonical translates as "humanity to others" or "I am what I am because of who we all are". Ubuntu is built on Debian's architecture and infrastructure, comprises Linux server and discontinued phone and tablet operating system versions.
Ubuntu releases updated versions predictably every six months, each release receives free support for nine months with security fixes, high-impact bug fixes and conservative beneficial low-risk bug fixes. The first release was in October 2004. Current long-term support releases are supported for five years, are released every two years. LTS releases get regular point releases with support for new hardware and integration of all the updates published in that series to date. Ubuntu packages are based on packages from Debian's unstable branch. Both distributions use package management tools. Debian and Ubuntu packages are not binary compatible with each other, however, so packages may need to be rebuilt from source to be used in Ubuntu. Many Ubuntu developers are maintainers of key packages within Debian. Ubuntu cooperates with Debian by pushing changes back to Debian, although there has been criticism that this does not happen enough. Ian Murdock, the founder of Debian, had expressed concern about Ubuntu packages diverging too far from Debian to remain compatible.
Before release, packages are imported from Debian unstable continuously and merged with Ubuntu-specific modifications. One month before release, imports are frozen, packagers work to ensure that the frozen features interoperate well together. Ubuntu is funded by Canonical Ltd. On 8 July 2005, Mark Shuttleworth and Canonical 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 goal. On 12 March 2009, Ubuntu announced developer support for third-party cloud management platforms, such as those used at Amazon EC2. GNOME 3 has been the default GUI for Ubuntu Desktop since Ubuntu 17.10, while Unity is still the default in older versions, including all current LTS versions except 18.04 LTS. However, a community-driven fork of Unity 8, called Yunit, has been created to continue the development of Unity. Shuttleworth wrote on 8 April 2017, "We will invest in Ubuntu GNOME with the intent of delivering a fantastic all-GNOME desktop.
We're helping the Ubuntu GNOME team, not creating something different or competitive with that effort. While I am passionate about the design ideas in Unity, hope GNOME may be more open to them now, I think we should respect the GNOME design leadership by delivering GNOME the way GNOME wants it delivered. Our role in that, as usual, will be to make sure that upgrades, security and the full experience are fantastic." Shuttleworth mentioned that Canonical will cease development for Ubuntu Phone and convergence.32-bit i386 processors have been supported up to Ubuntu 18.04, but users "will not be allowed to upgrade to Ubuntu 18.10 as dropping support for that architecture is being evaluated". A default installation of Ubuntu contains a wide range of software that includes LibreOffice, Thunderbird and several lightweight games such as Sudoku and chess. Many additional software packages are accessible from the built in Ubuntu Software as well as any other APT-based package management tools. Many additional software packages that are no longer installed by default, such as Evolution, GIMP, Synaptic, are still accessible in the repositories still installable by the main tool or by any other APT-based package management tool.
Cross-distribution snap packages and flatpaks are available, that both allow installing software, such as some of Microsoft's software, in most of the major Linux operating systems. The default file manager is GNOME Files called Nautilus. Ubuntu operates under the GNU General Public License and all of the application software installed by default is free software. In addition, Ubuntu installs some hardware drivers that are available only in binary format, but such packages are marked in the restricted component. Ubuntu aims to be secure by default. User programs can not corrupt the operating system or other users' files. For increased security, the sudo tool is used to assign temporary privileges for performing administrative tasks, which allows the root account to remain locked and helps prevent inexperienced users from inadvertently making catastrophic system changes or opening secu
A database is an organized collection of data stored and accessed electronically from a computer system. Where databases are more complex they are developed using formal design and modeling techniques; the database management system is the software that interacts with end users and the database itself to capture and analyze the data. The DBMS software additionally encompasses; the sum total of the database, the DBMS and the associated applications can be referred to as a "database system". The term "database" is used to loosely refer to any of the DBMS, the database system or an application associated with the database. Computer scientists may classify database-management systems according to the database models that they support. Relational databases became dominant in the 1980s; these model data as rows and columns in a series of tables, the vast majority use SQL for writing and querying data. In the 2000s, non-relational databases became popular, referred to as NoSQL because they use different query languages.
Formally, a "database" refers to the way it is organized. Access to this data is provided by a "database management system" consisting of an integrated set of computer software that allows users to interact with one or more databases and provides access to all of the data contained in the database; the DBMS provides various functions that allow entry and retrieval of large quantities of information and provides ways to manage how that information is organized. Because of the close relationship between them, the term "database" is used casually to refer to both a database and the DBMS used to manipulate it. Outside the world of professional information technology, the term database is used to refer to any collection of related data as size and usage requirements necessitate use of a database management system. Existing DBMSs provide various functions that allow management of a database and its data which can be classified into four main functional groups: Data definition – Creation and removal of definitions that define the organization of the data.
Update – Insertion and deletion of the actual data. Retrieval – Providing information in a form directly usable or for further processing by other applications; the retrieved data may be made available in a form the same as it is stored in the database or in a new form obtained by altering or combining existing data from the database. Administration – Registering and monitoring users, enforcing data security, monitoring performance, maintaining data integrity, dealing with concurrency control, recovering information, corrupted by some event such as an unexpected system failure. Both a database and its DBMS conform to the principles of a particular database model. "Database system" refers collectively to the database model, database management system, database. Physically, database servers are dedicated computers that hold the actual databases and run only the DBMS and related software. Database servers are multiprocessor computers, with generous memory and RAID disk arrays used for stable storage.
RAID is used for recovery of data. Hardware database accelerators, connected to one or more servers via a high-speed channel, are used in large volume transaction processing environments. DBMSs are found at the heart of most database applications. DBMSs may be built around a custom multitasking kernel with built-in networking support, but modern DBMSs rely on a standard operating system to provide these functions. Since DBMSs comprise a significant market and storage vendors take into account DBMS requirements in their own development plans. Databases and DBMSs can be categorized according to the database model that they support, the type of computer they run on, the query language used to access the database, their internal engineering, which affects performance, scalability and security; the sizes and performance of databases and their respective DBMSs have grown in orders of magnitude. These performance increases were enabled by the technology progress in the areas of processors, computer memory, computer storage, computer networks.
The development of database technology can be divided into three eras based on data model or structure: navigational, SQL/relational, post-relational. The two main early navigational data models were the hierarchical model and the CODASYL model The relational model, first proposed in 1970 by Edgar F. Codd, departed from this tradition by insisting that applications should search for data by content, rather than by following links; the relational model employs sets of ledger-style tables, each used for a different type of entity. Only in the mid-1980s did computing hardware become powerful enough to allow the wide deployment of relational systems. By the early 1990s, relational systems dominated in all large-scale data processing applications, as of 2018 they remain dominant: IBM DB2, Oracle, MySQL, Microsoft SQL Server are the most searched DBMS; the dominant database language, standardised SQL for the relational model, has influenced database languages for other data models. Object databases were developed in the 1980s to overcome the inconvenience of object-relational impedance mismatch, which led to the coining of the term "post-relational" and the development of hybrid object-relational databas
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
Mozilla is a free software community founded in 1998 by members of Netscape. The Mozilla community uses, develops and supports Mozilla products, thereby promoting free software and open standards, with only minor exceptions; the community is supported institutionally by the not-for-profit Mozilla Foundation and its tax-paying subsidiary, the Mozilla Corporation. Mozilla's products include the Firefox web browser, Thunderbird e-mail client, Firefox OS mobile operating system, Bugzilla bug tracking system, Gecko layout engine, Pocket "read-it-later-online" service, others. According to web browsers usage statistics, Mozilla's Firefox trails behind Google Chrome. On January 23, 1998, Netscape made two announcements: first, that Netscape Communicator would be free. One day Jamie Zawinski, from Netscape, registered mozilla.org. The project took its name, "Mozilla", after the original code-name of the Netscape Navigator browser — a portmanteau of "Mosaic and Godzilla", used to co-ordinate the development of the Mozilla Application Suite, the open-source version of Netscape's internet software, Netscape Communicator.
Jamie Zawinski says. A small group of Netscape employees were tasked with coordination of the new community. Mozilla aimed to be a technology provider for companies, such as Netscape, who would commercialize their open-source code; when AOL reduced its involvement with Mozilla in July 2003, the Mozilla Foundation was designated the legal steward of the project. Soon after, Mozilla deprecated the Mozilla Suite in favor of creating independent applications for each function the Firefox web browser and the Thunderbird email client, moved to supply them directly to the public. Mozilla's activities have since expanded to include Firefox on mobile platforms, a mobile OS called Firefox OS, a web-based identity system called Mozilla Persona and a marketplace for HTML5 applications. In a report released in November 2012, Mozilla reported that their total revenue for 2011 was $163 million, up 33% from $123 million in 2010. Mozilla noted that 85% of their revenue comes from their contract with Google. At the end of 2013, Mozilla announced a deal with Cisco Systems whereby Firefox would download and use a Cisco-provided binary build of an open source codec to play the proprietary H.264 video format.
Eich's donation first became public knowledge in 2012, while he was Mozilla’s chief technical officer, leading to angry responses on Twitter—including the use of the hashtag "#wontworkwithbigots". Protests emerged in 2014 following the announcement of Eich's appointment as CEO of Mozilla. U. S. companies OkCupid and CREDO Mobile received media coverage for their objections, with the former asking its users to boycott the browser, while Credo amassed 50,000 signatures for a petition that called for Eich's resignation. Due to the controversy, Eich voluntarily stepped down on April 3, 2014 and Mitchell Baker, executive chairwoman of Mozilla Corporation, posted a statement on the Mozilla blog: "We didn't move fast enough to engage with people once the controversy started. Mozilla believes both in freedom of speech. Equality is necessary for meaningful speech, and you need free speech to fight for equality." Eich's resignation promoted a backlash. OkCupid co-founder and CEO Sam Yagan had donated $500 to Republican candidate Chris Cannon who proceeded to vote for multiple measures viewed as "anti-gay", including the banning of same-sex marriage.
Private browsing, privacy mode or incognito mode is a privacy feature in some web browsers to disable browsing history and the web cache. This allows a person to browse the Web without storing local data that could be retrieved at a date. Privacy mode will disable the storage of data in cookies and Flash cookies; this privacy protection is only within the browser application as it may leave traces on the hard drive and memory of the device, or via websites by associating the IP address at the web server. The earliest reference to private browsing was in May 2005, was used to discuss the privacy features in the Safari browser bundled with Mac OS X Tiger; the feature has since been adopted in other browsers, led to popularization of the term in 2008 by mainstream news outlets and computing websites when discussing beta versions of Internet Explorer 8. However, privacy modes operate as shields because browsers do not remove all data from the cache after the session. Plug-ins, like Silverlight, are able to set cookies.
The common web browser plugin Adobe Flash Player began supporting privacy mode in Chrome, Internet Explorer, Safari with the release of version 10.1 in June 2010.. Some browsers allow users to select the privacy mode for single tabs, whereas others create a more isolated environment protected by password and cryptography. Private browsing has multiple uses, including: Reducing history, including autofill and personal information. Performing "pure searches" that are not influenced by prior browsing history or networks or friends' recommendations, which may weight and more rank certain results than others. Preventing accidental saving of login credentials to accounts. Signing into multiple accounts via multiple tabs. Testing websites. Preventing other users of the computer from finding one's search history. Viewing explicit material without outside knowledge; the Mozilla Foundation performed a study about the user behavior when the feature is switched on and how long the session lasts. The results were that most sessions last only about 10 minutes, though there are periods where activation increases.
Private browsing is known by different names in different browsers. In 2012, Brazilian researchers published the results of a research project where they applied forensic techniques to extract information about the users browsing activities on Internet Explorer and Firefox browsers with their private mode enabled, they were able to collect enough data to identify pages visited and partially reconstruct them. This research was extended to include Chrome and Safari browsers; the gathered data proved that browsers' private mode implementations are not able to hide users' browsing activities and that browsers in private mode leave traces of activities in caching structures and files related to the paging process of the operating system. Another independent security analysis, performed by a group of researchers at Newcastle University in 2014, shows a range of security vulnerabilities in the implementation of the private mode across four major browsers; the results are summarized below. Browser extensions are potential threats to the user privacy.
By design, existing browsers choose to enable extensions in the private mode by default. This however allows an installed extension to secretly record the visited websites without the user's awareness. Newer versions of Chrome disable extensions in the private mode by default, but allow the private and the normal modes to run in parallel; this makes it possible for an installed extension in the normal mode to learn the user activities in the private mode by measuring the usage of shared computing resources. Data erasure by the browser alone is found to be insufficient. For example, the records of visited websites during the private session can be retained in memory for a long time after the private session is closed. In addition, the visited website records are kept by the operating system in the local DNS cache. Furthermore, the modified timestamps of certain profile files saved on the disk may reveal if the private mode was turned on and when it was turned on. Software bugs present in some browsers are found to degrade the security of the private mode.
For example, in some earlier versions of Safari, the browser retained private browsing history records if the browser program was not closed or if the user acted to add a bookmark within the private mode. Depending on whether the session is in the private or the normal mode, web browsers exhibit different user interfaces and traffic characteristics; this allows a remote website to tell if the user is in the private mode, for example, by checking the color of the hyperlinks or measuring the time of writing cookies. In 2010, professors at Stanford University found that while Firefox won't record your history during a private browsing session, it still records the sites on which you've installed SSL certificates and allows specific permissions. If you download an SSL certificate from a website or told that site to stop displaying pop-ups and downloading cookies, all of that information is still stored on Firefox. In 2015, researchers from Pennsylvania State University found that a cons
In the context of the World Wide Web, a bookmark is a Uniform Resource Identifier, stored for retrieval in any of various storage formats. All modern web browsers include bookmark features. Bookmarks are called favorites or Internet shortcuts in Internet Explorer, by virtue of that browser's large market share, these terms have been synonymous with bookmark since the first browser war. Bookmarks are accessed through a menu in the user's web browser, folders are used for organization. In addition to bookmarking methods within most browsers, many external applications offer bookmark management. Bookmarks have been incorporated in browsers since the Mosaic browser in 1993. Bookmark lists were called Hotlists in previous versions of Opera. Other early web browsers such as ViolaWWW and Cello had bookmarking features. With the advent of social bookmarking, shared bookmarks have become a means for users sharing similar interests to pool web resources, or to store their bookmarks in such a way that they are not tied to one specific computer or browser.
Live bookmarks are updated automatically. Comparison of browser synchronizers Enterprise bookmarking Favicon Smart keyword Social bookmark link generator Social bookmarking XBEL Bookmark Managers at Curlie
An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may include accounting software for cost allocation of processor time, mass storage and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is executed directly by the hardware and makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer – from cellular phones and video game consoles to web servers and supercomputers; the dominant desktop operating system is Microsoft Windows with a market share of around 82.74%. MacOS by Apple Inc. is in second place, the varieties of Linux are collectively in third place. In the mobile sector, use in 2017 is up to 70% of Google's Android and according to third quarter 2016 data, Android on smartphones is dominant with 87.5 percent and a growth rate 10.3 percent per year, followed by Apple's iOS with 12.1 percent and a per year decrease in market share of 5.2 percent, while other operating systems amount to just 0.3 percent.
Linux distributions are dominant in supercomputing sectors. Other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can only run one program at a time, while a multi-tasking operating system allows more than one program to be running in concurrency; this is achieved by time-sharing, where the available processor time is divided between multiple processes. These processes are each interrupted in time slices by a task-scheduling subsystem of the operating system. Multi-tasking may be characterized in co-operative types. In preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, such as Solaris and Linux—as well as non-Unix-like, such as AmigaOS—support preemptive multitasking. Cooperative multitasking is achieved by relying on each process to provide time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking.
32-bit versions of both Windows NT and Win9x, used preemptive multi-tasking. Single-user operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem. A multi-user operating system extends the basic concept of multi-tasking with facilities that identify processes and resources, such as disk space, belonging to multiple users, the system permits multiple users to interact with the system at the same time. Time-sharing operating systems schedule tasks for efficient use of the system and may include accounting software for cost allocation of processor time, mass storage and other resources to multiple users. A distributed operating system manages a group of distinct computers and makes them appear to be a single computer; the development of networked computers that could be linked and communicate with each other gave rise to distributed computing. Distributed computations are carried out on more than one machine; when computers in a group work in cooperation, they form a distributed system.
In an OS, distributed and cloud computing context, templating refers to creating a single virtual machine image as a guest operating system saving it as a tool for multiple running virtual machines. The technique is used both in virtualization and cloud computing management, is common in large server warehouses. Embedded operating systems are designed to be used in embedded computer systems, they are designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited number of resources, they are compact and efficient by design. Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is an operating system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, it uses specialized scheduling algorithms so that a deterministic nature of behavior is achieved. An event-driven system switches between tasks based on their priorities or external events while time-sharing operating systems switch tasks based on clock interrupts.
A library operating system is one in which the services that a typical operating system provides, such as networking, are provided in the form of libraries and composed with the application and configuration code to construct a unikernel: a specialized, single address space, machine image that can be deployed to cloud or embedded environments. Early computers were built to perform a series of single tasks, like a calculator. Basic operating system features were developed in the 1950s, such as resident monitor functions that could automatically run different programs in succession to speed up processing. Operating systems did not exist in their more complex forms until the early 1960s. Hardware features were added, that enabled use of runtime libraries and parallel processing; when personal computers became popular in the 1980s, operating systems were made for them similar in concept to those used on larger computers. In the 1940s, the earliest electronic digital systems had no operating systems.
Electronic systems of this time were programmed on rows of mechanical switches or by jumper wires on plug boards. These were special-purpose systems that, for example, generated ballistics tables for the military or controlled the pri