non-volatile memory：What are non

Non-volatile memory (NVM) or non-volatile storage is a type of computer memory[1] that can retain stored information even after power is removed. In contrast, volatile memory[2] needs constant power in order to retain data. Examples of non-volatile memory include flash memory[3], read-only memory[4] (ROM), ferroelectric RAM[5], most types of magnetic computer storage[6] devices (e.g. hard disk drives[7], floppy disks[8], and magnetic tape[9]), optical discs[10], and early computer storage methods such as paper tape[11] and punched cards[12].[1] (https://en.wikipedia.org/wiki/Non-volatile_memory)

A solid-state drive (SSD) is a solid-state storage[13] device that uses integrated circuit[14] assemblies to store data persistently[15], typically using flash memory[16], and functioning as secondary storage[17] in the hierarchy of computer storage[18]. It is also sometimes called a solid-state device or a solid-state disk,[1] even though SSDs lack the physical spinning disks[1...