Character Sets and Collations in General

A character set is a set of symbols and encodings. A collation is a set of rules for comparing characters in a character set.
MySQL can do these things for you:

Store strings using a variety of character sets
Compare strings using a variety of collations
Mix strings with different character sets or collations in the same server, the same database, or even the same table
Enable specification of character set and collation at any level

In these respects, MySQL is far ahead of most other database management systems. However, to use these features effectively, you need to know what character sets and collations are available, how to change the defaults, and how they affect the behavior of string operators and functions.
Read more: CharacterSets/Collations