Part 1 of Essay
The most common way of storing data in a computer is magnetic. We have hard drives and floppy disks (soon making way to the CD-ROM), both of which can store some amount of data. In a disk drive, a read/write head (usually a coil of wire) passes over a spinning disk, generating an electrical current, which defines a bit a ....

Part 2 of Essay
.... a little bit, we can change tracks on a disk, and this movement is very small, usually less than a hairÕs width. This allows one to store an immense amount of data on one disk. The light does not touch the disk surface, thereby not creating friction, which leads to wear, so the life of an average optical disk is far longer than that of a magnetic medium. Also, it is impossible to ÒcrashÓ an optical disk (in the same sense as crashing a hard drive), since there is a protective layer covering the data areas, ....