EEPROM, (Pronounced double-e-p-rom, or e-e-p-rom), is short for Electrically Erasable Programmable Read Only Memory. EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. Like other types of PROM, EEPROM retains its contents even when the power is turned off. Also, like other types of ROM, EEPROM is not as fast as RAM.
EEPROM is similar to Flash Memory (sometimes called flash EEPROM). The principal difference is that EEPROM requires data to be written or erased one byte at a time, while flash memory allows data to be written or erased in blocks; this makes flash memory a faster alternative.