Flash memory
Beginner
Memory that keeps its data with the power off, used in phones, memory cards and SSDs. It stores bits by trapping electrons.
Novice
Non-volatile memory where each cell is a transistor with an extra, insulated charge-storage layer. Trapped electrons shift the transistor’s threshold voltage, and the threshold encodes the data. NAND flash chains cells in series for density.
Expert
Floating-gate or charge-trap transistors programmed and erased by Fowler–Nordheim tunneling through the tunnel oxide. Programmed page by page, erased block by block, with endurance of thousands of program/erase cycles. Multi-level cells store 2–4 bits by dividing the threshold window.
Explained in Memory cells (Transistors).
See also: Floating gate / charge trap, Multi-level cell (MLC, TLC, QLC), Volatile memory.