Root is the base level directory on a Linux system. webOS is at base, a Linux system. All branches of the file system and therefore the whole system stem from the root. Android is also a Linux based system that runs from a root directory. There is a technique known as chroot (change root) that enables you to run a second system within another by creating a subsystem in which the secondary system appears to have the root directory.
If you pay much attention to the shifts and changes in the mobile phone market, you will be aware that over the past couple of years there has been increasing consolidation. These days the market is dominated by Apple’s iphone and most of all, by the many models running the Android operating system. This system – at least in its basic form is open source software. Naturally, many developers therefore take advantage of this ‘off the shelf’ operating system. New entrants and existing challengers in the market have tried to leverage Android and specifically, it’s large app catalogue to gain an advantage. This includes Blackberry, Jolla (sailfishOS) and there are reports that even Microsoft are considering a means to run Android apps on Windows phone. There are also projects that offer existing Android users the opportunity to install a customised version. The most notable of these is Cyanogenmod, which can now be installed on a wide range of hardware.