LineageOS is an Android-based operating system for smartphones, tablet computers, and set-top boxes, with mostly free and open-source software. It is the successor to CyanogenMod, from which it was forked in December 2016, when Cyanogen Inc. announced it was discontinuing development and shut down the infrastructure behind the project. Since Cyanogen Inc. retained the rights to the Cyanogen name, the project rebranded its fork as LineageOS.
LineageOS was officially launched on 24 December 2016, with the source code available on both GitHub and GitLab. In March 2017, it reportedly had one million users with the OnePlus One being the most popular device.
CyanogenMod
CyanogenMod (often abbreviated "CM") was a popular open-source operating system for smartphones and tablet computers, based on the Android mobile platform. CyanogenMod users can opt-in to report their use of the firmware. In March 2015, Forbes indicated over 50 million people were running CyanogenMod on their phones.
In 2013, the founder, Stefanie Kondik, obtained venture funding under the name Cyanogen Inc. to allow commercialization of the project. In her view, the company did not capitalize on the project's success and in 2016 she either left or was forced out as part of a corporate restructure which involved a change of CEO, closure of offices and projects, and cessation of services. The code itself, being both open source and popular, was forked under the new name LineageOS and efforts began to resume development as a community project.
CyanogenMod offered a number of features and options not available in the official firmware distributed by most mobile device vendors. Features supported by CyanogenMod included native theme support, FLAC audio codec support, a large Access Point Name list, Privacy Guard (per-application permission management application), support for tethering over common interfaces, CPU overclocking, root access, soft buttons and other "tablet tweaks," toggles in the notification pull-down (such as Wi-Fi, Bluetooth and satellite navigation), and other interface and performance enhancements.