I’ve Always Wanted To Know:
Why do DVD/CD/Bluray Discs spin in your computer/player?
Optical Media (DVD/CD/Bluray) store information by burning or pressing very tiny pits on the surface of the disc. Your computer or player then shines a very narrow laser beam up at the disc and reads where a pit exists and where one doesn’t and translates that into the 0′s and 1′s (Binary) that a computer or electronic device can understand.
In order to read just the right pits your computer or player wants (Like a specific Song or part of a movie) the laser needs to move to just the right part of the disc. Just like a record player the creators of optical media realized that if you spin the disc around you can move the laser up and down a track and be able to read every part of the disc as it spins around. This spinning optical media allowed players to be much smaller and allows the information to be encoded in circles on the disc to be read very quickly as it passes over the laser.