optical,magnetic and solid state
solid state storage
A solid-state drive (SSD) (also known as a solid-state disk  or electronic disk, though it contains no actual "disk" of any kind, nor motors to "drive" the disks) is a data storage device using integrated circuit assemblies as memory to store data persistently. SSD technology uses electronic interfaces compatible with traditional block input/output (I/O) hard disk drives, thus permitting simple replacement in common applications. Also, new I/O interfaces like SATA Express are created to keep up with speed advancements in SSD technology.
SSDs have no moving mechanical components. This distinguishes them from traditional electromechanical magnetic disks such as hard disk drives (HDDs) or floppy disks, which contain spinning disks and movable read/write heads. Compared with electromechanical disks, SSDs are typically more resistant to physical shock, run more quietly, have lower access time, and less latency. However, while the price of SSDs has continued to decline in 2012, SSDs are still about 7 to 8 times more expensive per unit of storage than HDDs.