The type of flash memory used for solid state storage. NAND flash is like a hard drive, whereas NOR flash is like the computer's RAM. NAND cells are also more dense, more economical and are written faster than NOR cells. However, NOR offers faster read speed, which is why NOR is used for program execution. Just like programs on a hard drive, if software is stored in NAND, it is copied to RAM for execution. See flash memory and NAND.