Blu-ray is a new protocol for 5 1/4 inch optical disks. It uses a blue laser, which allows it to store a hell of a lot more data. There is a competing standard (of course!!!) which still uses a red laser (I think) and is called HD-DVD. Basically, both will allow an HD program on a 5 1/4 inch disk.

Me, I'm waiting for it to all shake out, just like SACD/DVD-A. It's really irritating...

I am the Doctor, and THIS... is my SPOON!