Often these ROMs add options that would not usually be present through an official update of Lenovo A319. In other words, the custom ROM modifies the so-called kernel of your Lenovo A319 (the core of the operating system), changing its functionality. The operation of a custom ROM is quite simple. The original ROM is called the stock ROM. However, some ROMs, referred to as custom ROMs, were explicitly modified to act on the standard functionality of the factory OS. This means that, in everyday use, a regular user cannot go and edit system files. In smartphones, ROM represents the operating system installed in the physical memory of the device.

The term ROM stands for Read-Only Memory and represents volatile read-only memory.