At its core, Endless OS is a Linux distribution based on Debian.
However, it is not based on Debian in the same way that Ubuntu is based on Debian. The main difference is the Endless OS use OSTree + Flatpak to manage the base system and applications, unlike Debian/Ubuntu that uses .deb packages for the system and applications.
The reason we use OSTree management is that it is a more robust system because the classic situation of updating a package and breaking the system does not happen in this method.
Most desktop Linux distributions are oriented towards tech-savvy users and developers, but Endless OS isn't your typical Linux distribution. We have a different target user. We don’t use rpm, apt, or any other packaging system. We use a read-only root file system managed by OSTree with apps installed using Flatpak.
You may notice that the apt-get and dpkg commands are installed. This is because Endless OS is based on Debian, and these commands are used while creating Endless OS. Each release is a read-only snapshot, so you can use commands like dpkg -l which do not make changes to the system, but you cannot use commands like apt-get install.
Almost all of the software that makes up Endless OS is Free and Open Source Software, and the source code is available through our website. You may of course download, modify and replace any component of Endless OS as is permitted by the open source licenses, but doing so may break your ability to receive further software updates from Endless.
For advanced Endless OS technical topics, see the Development documentation.
Endless OS is built on top of decades of efforts from the free and open-source software community, and we acknowledge a great debt to it. We contribute back to open source projects whenever we can, and are recognised as key contributors to projects such as GNOME and Flatpak.
Our OS does contain a small number of components that are not open source. We are working on removing these going forward; see the PAYG FAQ for more information.
For more information on the open-source software used to build Endless OS, see the Developers page.
No, there is no real need for a recovery partition on Endless OS.
Endless OS is structured very differently from other operating systems. On other platforms, it is very easy for you to install something which actually modifies the OS and transforms it into something slightly different, perhaps in a problematic way. And if you upgrade from (e.g.) Windows 8 to Windows 10, you'll potentially be running an OS with pronounced differences compared to if you had installed Windows 10 from scratch. This leads to many common situations on other platforms where doing an OS reset to a pristine version from a recovery partition actually makes a user-visible difference, and can solve common problems.
Endless features a more robust design. The OS is regarded as an immutable unit. It is not possible for an ordinary user or app installation to modify it. If you do an OS update, you end up with the same OS as if you had installed the new version from scratch. Because the OS is always pristine and never modified, there is nothing to reset, so there is no reason for us to sacrifice a lot of disk space to a hidden recovery partition.
Users and partners that observe problems on other platforms that can be corrected by restoring from a recovery partition simply should not expect the same class of problems to occur under Endless OS.