Restore Ramdisk

From The Apple Wiki

Wipes everything out on the NAND and reflashes it with the OS provided in the IPSW. After, it will flash the NOR with the firmware files in the IPSW, and if it is an iPhone, re-flash the baseband as well (provided it is not an earlier baseband version, except in the case of the iPhone 4 and newer which depends on whether or not Apple is signing the baseband firmware you are trying to flash). On iPhone 5S and newer, it's also responsible for updating the SEP via seputil