ROM ka full form

well it stands for Read Only Memory .
ROM is a non-volatile memory and it can be called as the permanent memory even though the power is turned off the data present in the memory doesn’t change.
ROM is used to store firmware for the hardware which will not be updated regularly.  The data on the traditional forms of RAM is hardwired to it, that is written at the time of manufacturing. Since a long time, the read-only memory has been developed to support erasing, rewriting of the data although it can’t achieve the efficiency level of Random Access Memory.