Like CDs and DVDs, Blu-ray is an optical disc media. It was created for keeping a lot of data as well as for capturing and watching back HD video. A single Blu-ray disc can store up to 25 GB of data, compared to a CD's 700 MB and a standard DVD's 4.7 GB. Only 17 Gigabytes of info can fit on a double-sided, dual-layer Disc (which are uncommon). Blu-ray DVDs with two layers will be able to hold 50 Gigabytes of info. It's the same as 4 hours of UHD.

Due to the use of blue lasers in the disks, Blu-ray discs can store more data than other optical media. Although the laser is technically blue-violet, the word "Blu-ray" is a little simpler to say than "Blu-violet-ray." Compared to red lasers used to create Discs and DVDs, the blue-violet laser has a lower range (405nm compared to 650nm). As a result, much more data can be fit on a platter the same size as a CD or DVD by enabling the laser to concentrate on a tiny region. As more people switch to HDTV, Blu-ray format supporters predict that Blu-ray players will eventually supplant DVD cameras and VCRs (thank heavens).