How does a CD store its information?

Answer 1

If you were to look at the shiny part of a disc under a microscope, you'll see that its covered with little dents (called pits, which are small indentations on the surface). The smooth parts of the disc between the pits are called lands.
See image: http://www.sonic.net/~ideas/art_mma3.htm…

When a laser is shone on the disc and the disc is spun, the smooth parts of the disc, called the 'lands' bounces the laser back onto the sensor.
Everytime this happens, it registers as a "1" in computer binary code.
However, as it hits a pit (dent), this disrupts the laser beam and thus the laser misses the sensor in the disc drive.
This registers as a "0" in binary code.

As the disc spins, a sequence of 1's and 0's is produced by the 'pits' and "lands" is produced. The computer analyzes this code and then turns it into data.