Optical, magnetic and solid state
By Daniel Chung
CDs DVDs and other forms of disk which use marks in the disk to store patterns are all optical storage memory forms. Data is recorded by making marks in a pattern which can be read back with the aid of light, which usually is a focused beam of light precisely focused on a spinning disk.
Solid state memory
The term 'solid state essentially means 'no moving parts'. Solid-state storage devices are based on electronic circuits with no moving parts (no reels of tap, no spinning discs, no laser beams, etc.) Solid state devices store data using a special type of memory called flash memory. Flash memory is a type of electronically- erasable programmable read-only memory (EEPROM). Flash memory is non-volatile (like ROM) but data is stored in it can also be erased or changed (like RAM).
Flash memory can be found in many data storage devices.
Some examples of solid state memory are:
USB Memory Sticks
Smart Cards-chip and pin cards