Floating gate / charge trap
Beginner
An island inside a flash transistor, walled off by insulation, where electrons can be parked for years.
Novice
A flash cell’s storage layer. A floating gate is a conductor completely surrounded by oxide; a charge trap is an insulating layer (silicon nitride) that holds electrons in traps. Either way, stored charge raises the transistor’s threshold voltage.
Expert
Floating gates (planar NAND) store charge on a conductor, so one leak path drains the whole gate; charge-trap layers (most 3D NAND) store it in discrete traps, tolerate oxide defects better and endure more cycles, but lose charge faster soon after programming, including sideways between cells.