There are three types of Flash Memory: NOR Serial Flash, NOR Parallel Flash, and NAND Flash. NOR Serial Flash has exceptionally high reliability and low power consumption, but it is unsuitable for high density and low writing speed. NOR Parallel Flash has higher speed than Serial Flash but lower density. NAND Flash has higher density but slow reading time and less reliability than NOR Flash. Each Flash memory type has inherent merit and demerit. Careful consideration must be used to select the correct Flash memory depending on the application.