Optical storage is an electronic storage medium It uses low-power laser beams to record and retrieve digital (binary) data. Optical Devices: CD, DVD, and Blu-ray. Blu-ray uses blu-lasers to hold-up to 25 GB of data. The basic operation: READ Every optical disc is able to be read. The disc can be only written one time which cannot be erased. It is cheaper. If the disc can be erased, it is able to be used multiple times. ROM: Read Only Memory RAM: Random Access Memory