what is blue-ray?

Answer 1

It's a way of recording data on a disk like a CD or DVD, but it uses a blue laser to etch and read the data. It works by etching tiny pits in the surface of the disk to represent the data.

The blue color is significant because it has a smaller wavelength, so it can read and write smaller pits in the disk. That means you can get more information into the same space, so you can fit a whole movie, or even 3-4 movies, on one small disk.

Think of it this way - imagine writing a note to someone using a pencil. Now imagine writing it with a big black permanent marker, with a tip that's 1/2 inch wide. The bigger utensil makes it hard to write small letters. But using the smaller one lets you write more info in a smaller space.

Answer 2

normal dvd's and cd's use a red laser light to read the media.
blu ray and HD-DVD use a blue light. the difference is the wave length of light being used. since the wave lignth is longer in blue then red the bluray disk can hold more readable information.