If you've recently shopped for DVDs to watch, you may have come across the term 'Blu-ray'. Blu-ray discs are one of the latest technological sensations (not to be confused with 'bluetooth', which is a mobile phone technology). Blu-ray gets its name from the blue laser that reads this kind of disc. The big advantage of Blu-ray is that it can store a lot more data than the conventional DVD.

DVDs and the like are known as optical discs. The quest to develop better quality optical discs focused on the way they are read by machines. DVDs and CDs use a red or near-infrared laser beam. Blu-ray uses a violet (blue) laser beam with a shorter wavelength. That allows a great deal more information to be written to the disc. The key difference is that a blue laser can be focussed on a much smaller point on the disc's surface. The result is that a Blu-ray disc (BD for short) can store six to ten times more data than ordinary DVDs: as much as 50 gigabytes.

The race to reach the next level in optical discs involved a format battle between manufacturing giants, reminiscent of the VHS v. Betamax war over video formats. Toshiba's competitor product, the HD disc (high definition) finally lost out to Blu-ray technology. The factor that is widely believed to have tipped the balance was Sony's decision to include a Blu-ray player in the Playstation 3.

What exactly is a Blu-ray disc?

Like the DVD, Blu-ray is also a digital, optical storage medium. It is capable of storing five times as much data as a DVD, meaning it can contain a full movie in HD quality, along with multichannel sound and masses of bonus material.

The Blu-ray takes its name from the blue laser that players use to read the disc's data. The first Blu-ray discs hit the market in fall 2006, coinciding with the release of the first Blu-ray player, the Samsung BD-P 1000.

Is the picture quality of Blu-ray discs better than that of DVDs?

Yes. Sharpness, detail reproduction, color - everything is better! The five-fold increase in resolution results in a huge qualitative gain. Every Blu-ray disc we've tested so far has comprehensively trounced its DVD counterpart. Even the less clued-in users will notice the difference immediately, and the bigger the screen, the more obvious the difference will be.

How consistent is the increase in quality?

It's not always the same. Extremely expensive, elaborate Blu-ray productions, such as "Casino Royale" or "Mission: Impossible 3", will beat the corresponding DVDs by light-years. Blu-ray versions of older movies, such as "The Silence of the Lambs" or "Rocky", often show only a slight improvement over the DVD, unless the movie been remastered.

Can Blu-ray players also play DVDs and CDs?

Yes, they can, but DVD playback exhibits considerable differences in quality compared to Blu-ray playback. No wonder: Here, the device has to both de-interlace the signal and up-scale it to 1080p.

Very few Blu-ray players play back DVDs in top quality, and those that can are largely found in the higher price range. An insider's tip: The PlayStation 3 plays back both DVDs and Blu-rays excellently.

Can DVD players play back Blu-ray discs?

No, they can't. This has to do at the laser that's used to read the disc. The data tracks on a Blu-ray are very much finer, meaning the laser beam must also be significantly smaller. For the DVD, players use a laser on a wavelength of 650 nanometers, while Blu-rays require a laser on the wavelength of 405 nanometers.

Costs, movie selection, and future proofing:

Is switching to Blu-ray worthwhile?

Is now a good time to buy a Blu-ray player?

Yes, now is a good time. New Blu-ray players are now very sophisticated and well beyond the teething problems of the early models.

What does a Blu-ray player cost?

Blu-ray players from well-known manufacturers currently range from around 180 GBP all the way up to more than 1,800 GBP.