Taken from a Google search:
NAND flash memory is a type of non-volatile storage
technology that does not require power to retain data.
An important goal of NAND flash development has been to reduce the cost per bit and increase
maximum chip capacity so that flash memory can compete
with magnetic storage devices like hard disks. NAND flash has
found a market in devices to which large files are frequently uploaded and replaced. MP3 players, digital cameras
and USB drives use NAND
NAND has a finite number of write cycles. NAND
failure is usually gradual as individual cells fail and overall performance degrades, a concept
known as wear-out.
To help compensate, some vendors overprovision
their systems by including more memory than is actually
When a NAND card wears out, the user simply buys a new one, and the device continues to
function. By passing the expense of additional storage on to the consumer, manufacturers have been
able to lower the price of consumer electronic devices significantly. New developments in NAND
flash memory technology are making the chips smaller, increasing the maximum read-write cycles and
lowering voltage demands.