Blu-ray is a kind of disc, like a DVD, but it can hold a much clearer picture — high-definition film and some games. You need a Blu-ray player to watch it. The name comes from the blue laser inside the machine: that blue light has a shorter wavelength than the red laser in a DVD player, so it can pack more information onto the disc. Though actually, the spelling drops the e in blue — Blu-ray, not Blue-ray — because it began as a brand name. People still say it, but streaming has made the discs less common than they were ten or fifteen years ago. You may also hear Blu-ray used for the player itself, a little loosely.