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What are Blu-Ray Discs?

L. S. Wynn
L. S. Wynn
L. S. Wynn
L. S. Wynn

Blu-ray discs are media devices that are most commonly used to archive and store high definition video content. They often look like standard CDs or DVDs at first glance, and they work in basically the same way. The biggest differences are their storage capacity and how they’re read by players and other receiving devices. In most cases these discs need their own dedicated players that read the discs with a blue laser rather than a standard red laser. Content producers often like releasing films and gaming content with this sort of high-powered technology because of all that it allows them to do: images can be sharper and more realistic, and more special features can be included.

Brief History of the Optical Disc

A blue-ray player.
A blue-ray player.

Disc technology has been a popular way to store music and video files for decades. 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 compact disc, or CD, became available. One compact disc was able to hold about 700 megabytes (MB) of data. The first CDs were used for audio albums, then grew to also hold some video and image content — supplemental material from musicians like music videos, for instance, or digital animation as for video games or gaming consoles.

Blue-ray discs play movies in high definition.
Blue-ray discs play movies in high definition.

In the 1990s, digital video disc (DVD) technology became popular and ultimately became mainstream in many markets by the early 2000s. DVDs look just like a CD on the outside but are able to hold much more data. In general, one DVD has the storage capacity for one standard-length movie and, depending on the specifics, can usually also hold some bonus material.

Changes with High Definition

A stack of blu-ray discs.
A stack of blu-ray discs.

Blu-ray is the next iteration on the optical disc timeline. It was established to hold a feature-length movie in high-definition television (HDTV) format. Such movies are displayed in significantly higher resolution and therefore they require much more storage space. A disc usually holds about 27 gigabytes (GB) of information, which is about 40 times the amount of data that a standard CD can hold and at least 10 times the storage of a regular DVD.

Technology Differences

Blu-ray disks feature HD quality movies and can be played back using a special Blu-ray player.
Blu-ray disks feature HD quality movies and can be played back using a special Blu-ray player.

Aside from storage concerns, the fundamental difference between these and older CDs and DVDs is the laser that is used to read the discs. Blu-ray machines use a blue laser instead of the red lasers that are used to read earlier discs. Blue lasers have a shorter wavelength, usually about 450 nanometers, than do red lasers, which usually measure in around 650 nanometers. As such, the beam can be focused on a much smaller area. Practically speaking, this means that producers and content developers can put much more data on a single disc.

The blue laser also means that these discs are not readable on standard CD and DVD players and readers, though. In almost all cases consumers must buy a dedicated device in order to show these sorts of features. Putting one of these discs in a standard CD or DVD drive will usually result in an error message.

Many blue laser drives are what’s known as backward-compatible, however, which means that they are able to read more standard CDs and DVDs. Many feature an additional red laser, or they have the capability of switching between red and blue as needed for the disc. In part this is because manufacturers have realized that consumers who already own a lot of content in older formats may not be willing to repurchase everything in HD just for a better viewing experience, and this might be a hindrance to them buying new content in that format, too. By marketing players able to play both new and old discs, distributors hope to actually encourage more sales. Most scholars and researchers think that the growth of Blu-ray will parallel the increasing popularity of HDTV and overtake legacy systems at some point in the not too distant future.

Main Uses

The most popular use of this technology is movies and feature-length film projects, though serial television shows are often packaged and stored on these discs, too. They are also increasingly used to store video gaming content as they can create a more realistic virtual setting for players.

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Discussion Comments


@Azuza - It is annoying, but at least the new players can read the regular DVD's too. When DVD's first came out, they replaced tapes. And we all know there is no way to read a VHS tape on a DVD player!


I think it's extremely annoying how a lot of new media can't be read by the older media players. Was it really necessary to make Blu-Ray movies only readable by a special laser?

It seems highly suspect, because a lot of companies make money when everyone has to run out and buy new players. I personally don't plan on switching to Blu-Ray, because I'm going to keep my old DVD player until it wears out completely.


@Pharoah - I'm with you. I buy most stuff digitally, including movies, TV show episodes, and books. However, I think there are enough people who still like to purchase physical copies of things that Blu-Ray discs will remain popular and probably displace regular DVD's for most people.


I'm sure movies watched on Blu-Ray discs are of better quality than off of a standard DVD. However, I don't see myself even getting a cheap Blu-Ray player any time soon.

I haven't purchased any kind of movie disc in years! I pretty much buy all my content digitally, and I don't see that changing in the near future. It's much easier, I don't have to leave my house, and I don't have a ton of DVD's cluttering up my living room!


My little brother is crazy about movies and owns hundreds if not thousands of them. I have been amazed to see how many of his movies he is willing to buy new copies of now that they are available on blu-ray. It is the same movie, most of them do not even have new special features. But he is such a single minded collector that he is willing to spend the money.


Where can I buy a cheap blu-ray player that is still well built and effective?

I have been thinking about getting a Blu-ray player but I am still kind of hesitant. Does anyone have one?

I am wondering if the jump in quality is really that huge? Is Blu-ray that much better than DVD? And how do I know that there won't be a new technology in just a few years?


How much do they cost? Can you copy something to them?


Can these discs be written as music cd's like the standard cd-r?

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    • A blue-ray player.
      By: Alexander Orlov
      A blue-ray player.
    • Blue-ray discs play movies in high definition.
      By: cristi lucaci
      Blue-ray discs play movies in high definition.
    • A stack of blu-ray discs.
      A stack of blu-ray discs.
    • Blu-ray disks feature HD quality movies and can be played back using a special Blu-ray player.
      By: thawats
      Blu-ray disks feature HD quality movies and can be played back using a special Blu-ray player.