How does CD-rom works?

Answer 1

Simplified:

A laser burns small grooves into the surface of the CD. The grooves have pulses in them which can later be read by a laser and detector. The pulses represent data, ones and zeros. Computers only know ones and zeros, so that works out just fine.

The groves are organized into concentric circles. Some of the groves have special purposes and are there to identify the location and size of data stored on the CD-Rom.

When your computer wants to read a file of a specific name, it searches the file TABLE, for the location and size of the named file, then the "read head" moves to that location and reads pulses that represent the data.