Electrically erasable programmable read only memory (EEPROM)
An EEPROM is a special type of PROM which can be erased by exposing it to an electrical charge. Like other kinds of PROM, EEPROM retains its contents even when power is turned off. Additionally, as with other types of ROM, EEPROM access time isn't as fast as RAM. EEPROMs are similar to flash memories (sometimes known as flash EEPROM). Principal difference is that an EEPROM requires data to be erased or written one byte at a time while a flash memory allows data to be erased or written in whole blocks.