The SSD controller, the NAND flash and, quite often, DRAM. Rather than storing data on disks, the SSD facts lives on NAND flash chips with thousands of small minimal cells to hold the electrons that sign-up because the 1s and 0s, kind of like how buckets hold drinking water. and https://socialbuzzfeed.com/story170711/new-step-by-step-map-for-hdd-2-5-sata3-ssd-for-desktop