By the way, Google is your friend. If you want to get information about such things, googling for it is a good way to start. I suggest reading:
http://encyclopedia.thefreedictionary.com/Chinese%20writing%20system
As Richard Cook has pointed out, the definitions that are used in the Unicode Standard are not always identical to the ones for more general use.
A good source for the former is the Unicode glossary
http://www.unicode.org/glossary/
A./
PS: You should probably read Chapters 2 and 12 of the Unicode
Standard as well.
