NAND flash memory is a type of non-volatile storage technology that retains data even when the power is turned off. It is widely used in devices like USB drives, solid-state drives (SSDs), and memory cards due to its ability to store large amounts of data in a compact form. This memory works by using a series of memory cells made from floating-gate transistors, which can be programmed and erased in blocks. NAND flash is faster than traditional hard drives and has no moving parts, making it more durable and energy-efficient for everyday use.