As we have seen in previous chapters, Android is based on Linux, so it also inherits the part that concerns user permissions. As with a standard Linux system, Android also manages everything through groups and users. In the default configuration, it's not possible to obtain administrator (root) access, in order to prevent tampering with the system. Also, with access to the whole operating system, it's easy to corrupt the system itself, accidentally or deliberately (for example, to steal user data using a virus).

Every Android app, when installed on the system, generates a new user and group, and inter-app communications are performed according to Android SDK constraints and protocols. Sometimes, though, it's useful to have complete control over the device, like, for example, when installing apps that manage CPU frequency and the CPU governor.

Now let's see how to obtain root access and what the implications of rooting the device are.