Blu-Ray discs are one of the newcomers on the optical disc scene. The first optical discs available to consumers were the large video laser discs that were marketed during the early 1970s. By the 1980s the familiar CD became available. One compact disc was able to hold about 700MB (megabytes) of data. The first CDs were used for audio albums.

In the 1990s DVD (digital video discs) became popular. DVDs are the identical form factor of a CD but are able to hold much more data. The format was agreed upon because one DVD can hold a standard-length movie.

Blu-Ray is the next iteration on the optical disc timeline. The Blu-Ray standard was established to hold a standard-length movie in HDTV format, or high-definition television. Such movies are displayed in significantly higher resolution and therefore they require much more storage space. A standard Blu-Ray disc holds 27GB (gigabytes) of information which is about 40 times the amount of data that a CD can hold.

Although the technology is identical to CDs and DVDs, the fundamental difference with Blu-Ray is the laser that is used to read the discs. A blue laser (hence the name Blu-Ray) is used instead of the red lasers that are used on earlier discs. Blue lasers have a shorter wavelength (450 nanometers) than red lasers (650 nanometers), and therefore the beam can be focused on a smaller area which means that you can cram more data on an identically sized disc.

The new laser means that Blu-Ray discs are not readable on standard CD and DVD players and readers. Many Blu-Ray drives, however, will be backwards-compatible so they will be able to playback the older disc formats. The growth of Blu-Ray is expected to parallel the increasing popularity of HDTV and overtake legacy systems.