Optical storage is any storage method in which data is written and read with a laser for archival or backup purposes. Typically, data is written to optical media, such as CDs and DVDs. For several years, proponents have spoken of optical storage as a near-future replacement for both hard drives in personal computers and tape backup in mass storage.
Optical media is more durable than tape and less vulnerable to environmental conditions. On the other hand, it tends to be slower than typical hard drive speeds, and to offer lower storage capacities. According to OSTA (Optical Storage Technology Association), current optical speeds are approaching those of hard drives. A number of new optical formats, such as Blu-ray and UDO (ultra density optical), use a blue laser to dramatically increase capacities.