Flash memory is a non-volatile computer electronic storage medium that erases data in units of blocks and rewrites data at the byte level. A flash memory device usually consists of one or more flash memory chips and a separate flash memory controller chip. Because the erase cycle is prolonged, flash memory makes it have a significant speed advantage over non-flash EEPROM when writing a large amount of data. As of 2019, the cost of flash memory is much lower than byte-programmable EEPROM. Flash memory has become the primary memory type wherever a system requires a large amount of non-volatile solid-state storage. Flash memory is widely used for storage and data transmission in consumer devices, enterprise systems, and industrial applications. Regardless of whether the device equipped with flash memory is powered on or off, flash memory will retain data for an extended time.