The elementary OS project aims to solve a number of perceived deficiencies in the established desktop environments:Better global aesthetics by streamlining the user interface
Reduce software dependency by using core applications written in the C language or Vala
Diminish the need to access the terminal
Although not contrary to the GNU philosophy, these deliberate design choices diverge from what most GNU/Linux distributions opt for: a freedom to set up and customize one's own desktop environment. The Human Interface Guidelines of the elementary OS project focus instead on immediate usability with a gentle learning curve, rather than full-fledged customization. The three core rules the developers set for themselves were "concision", "avoid configuration" and "minimal documentation".
Pantheon's main shell is deeply integrated with other elementary OS applications like Plank (a dock), Epiphany (the default web browser) and Scratch (a simple text editor). This distribution uses Gala as its window manager, which is based on Mutter.
Pantheon is built on top of the GNOME software base, i.e. GTK+, GDK, Cairo, GLib (including GObject and GIO), GVfs and Tracker
Pantheon applications are either forks of current or older GNOME applications or written from scratch:Pantheon Greeter: Session manager based on LightDM
Wingpanel: Top panel, similar in function to GNOME Shell's top panel
Slingshot: Application launcher located in WingPanel
Plank: Dock (upon which Docky is based)
Switchboard: Settings application (or control panel)
Web: Web browser based on WebKitGTK+
Mail: Email client written in Vala
Maya: Desktop calendar
Noise: Audio player
Scratch: Simple text editor, comparable to gedit or leafpad
Pantheon Terminal: Terminal emulator
Pantheon Files (formerly called Marlin): File manager
Bryan Lunduke of Network World wrote that the Pantheon desktop environment, the centerpiece of the operating system, was among the best in 2016.
The elementary OS distribution initially started as a set of themes and applications designed for Ubuntu which later turned into its own Linux distribution. Being Ubuntu-based, it is compatible with its repositories and packages and uses Ubuntu's own software center to handle installation/removal of software. Its user interface aims at being intuitive for new users without consuming too many resources.
elementary OS is based on Ubuntu's Long Term Support releases, which its developers actively maintain for bugs and security for years even as development continues on the next release.
elementary OS founder Daniel Foré has said that the project is not designed to compete with existing open source projects but to expand their reach. The project also seeks to create open source jobs through developer bounties placed on specific development tasks. As of the 2016 Loki release, US$17,500 had been raised in bounties.
The first stable version of elementary OS was Jupiter, published on 31 March 2011 and based on Ubuntu 10.10. Since October 2012, it is no longer supported and thus no longer available for download in elementary OS official web site apart from in a historical capacity.
In November 2012, the first beta version of elementary OS code-named Luna was released, which uses Ubuntu 12.04 LTS as a base. The second beta version of Luna was released on 6 May 2013, carrying more than 300 bug fixes and several changes such as improved support for multiple localizations, multiple display support and updated applications. On 7 August 2013, a countdown clock appeared on the official website with a countdown to 10 August 2013. The second stable version of elementary OS, Luna, was released that same day, along with a complete overhaul and redesign of the elementary OS website.
The name of the third stable version of elementary OS, Isis, was proposed in August 2013 by Daniel Foré, the project leader. It was later changed to Freya to avoid association with the terrorist group ISIS. It is based on Ubuntu 14.04 LTS, which was released in April 2014. The first beta of Freya was released on 11 August 2014. The second beta of Freya was released on 8 February 2015. The final version was released on 11 April 2015, after a countdown clock appeared on the website eight days before its release.
Freya was downloaded 1.2 million times. In line with elementary's intent to expand the reach of open source software, 73 percent of Freya downloads were from closed source operating systems.
In 2015, the elementary OS developers changed the download page to default to a monetary amount before providing a direct HTTP download for the current stable release. Despite the fact that the user was able to supply any amount, or no amount at all, it sparked controversy about how such practices are typically not perceived as being in alignment with FOSS distribution philosophies. The elementary OS team has defended the action stating that "Around 99.875% of those users download without paying", and have justified an amount populating by default as a measure to ensure the continued development of the distribution.
In a review of all Linux distributions, Linux.com gave elementary OS their "best-looking distro" superlative in early 2016. The reviewer noted its developers' design background, their influence from Mac OS X, and their philosophy of prioritizing strict design rules and applications that follow these rules.
elementary OS 0.4, known by its codename, "Loki", was released on 9 September 2016. Loki was built atop the Ubuntu "long-term support" version released earlier in the year and its updated kernel (4.4). Loki revamped the operating system's notifications and added multiple new pieces of standard software. It let users set preferences for how their notifications display. Updated notification menu bar indicators began to display information from the notification—such as the title of an email—rather than a general alert. The operating system also added a system-wide integration for online accounts for Last.fm and FastMail, with other services in development.
Loki replaced Freya's Midori web browser with Epiphany, a WebKit2 browser with better performance. When the developers of the Geary email application dissolved, elementary OS forked Geary as "Mail" and added new visual and integration features. In a new calendar feature, users could describe events in natural language, which the calendar program interprets and places into the proper time and description fields when creating events.
elementary OS also created its own app store that simplifies the process of installing and updating applications. Project founder Daniel Foré called the AppCenter the biggest feature in the Loki release, and noted its speed improvement over other installation methods and internal development benefits for departing from Ubuntu's upgrade tools. Loki developers received $9,000 in bounties during its development—nearly half of the project's total bounty fundraising.
Jack Wallen of Linux.com praised Loki as among the most elegant and best designed Linux desktops. He found the web browser and app store changes to be significant improvements, and the email client revamp "a much-needed breath of fresh air" in a stagnating field. Overall, Wallen surmised that existing users would appreciate Loki's polish and new users would find it to be a perfect introduction to the operating system. Bryan Lunduke of Network World lauded Loki's performance, usability, polish, and easy installation, but considered it a better fit for new Linux users than for those already established.
Future elementary OS support for self-contained programs like Snappy or Flatpak is planned.