How do SSD HDs hold info if the system is unplugged from an electric source?

SSDs hold information even when unplugged because they use NAND flash memory, which is a type of non-volatile memory.

Each storage cell in an SSD is basically a special kind of transistor with an extra "floating gate" that can trap electrons. Once trapped, the electrons stay there because the floating gate is insulated. This keeps the charge in place even if there’s no power.