3d memory is a research field and technological concept centered on designing and implementing memory architectures where storage elements are arranged vertically in three dimensions, enabling significantly higher storage density than planar designs. This domain investigates the fabrication processes, structural variations (such as stacked cell strings), interface protocols, and performance characteristics of these vertically integrated structures, notably exemplified by 3D NAND flash memory, which has become the dominant non-volatile memory technology due to its capacity and cost advantages.