Hi, I having been looking on the internet and other threads and can't seem to find any detailed information on how a CD acts like a diffraction grating. What I understand: the CD has lots of little bumps which can split up light into its various colors. These colors can interfere constructively or destructively which gives the diffraction pattern. What I don't understand: the mechanism for why the light splits up. Why does white light simply hitting little bumps split the light up? For example, say you have the white light hitting a particular part of the bump why does this cause the colors split? Finally, why is this diffraction? I thought diffraction was the spreading out of waves which is why it is used to explain the fact we can hear sounds going around corners. I don't see how colors of light bouncing off at different angles from a CD has any similarity to what I have read diffraction to be? Many thanks for anyone who has time to help!