How does memory of mobile function ?

A mobile system's memory is comprised of following two types of memories:

1. RAM (Random Access Memory) — It is the work memory of the mobile system. The installed mobile apps, when run, are first loaded in the RAM and then executed. These apps remain in RAM and when you are no longer using them, then, they are shifted to background. RAM does not store information once the device is turned off.
2. ROM (Read Only memory) — The ROM or Read Only Memory is a part of mobile system's internal storage and it is not accessible for users to write on and is thus referred to as Read Only Memory. This ROM part of a mobile system internal storage is where operating system resides. It also has some preinstalled apps in this memory sections which cannot be deleted on users' end either.