An abstract notion of a list of characters in a specified
order.
Encoding
The encoding of a character set
is how its characters are represented in bits and bytes.
A character set may be encoded in different
encoding forms.
7-bit Encoding
Each character is encoded in one or more bytes depending on the
size of the character set.
Each byte is 8-bit long but the first bit is set to zero, so there are
only 7 variable bits. Some bytes, reserved for other purposes,
may not be used to encode printable characters. The best known
7-bit encoded character set is ASCII, in which every character is encoded in
exactly one byte. E-mail messages are usually sent in 7-bit
encoding because 8-bit or
16-bit encoded characters may not pass
correctly through some gateways.
8-bit Encoding
Each character is encoded in one or more bytes depending on the
size of the character set.
All 8 bits are variable but some bytes, reserved for other purposes,
may not be used to encode printable characters. The vast
marjority of web pages is written in 8-bit encoding.
16-bit Encoding
Each character is encoded in one or more pairs of
bytes. Some pairs of bytes may not be be used to encode printable
characters but any byte may occur within a pair.
UTF-16, the default
transformation format
of Unicode is a 16-bit
encoding form.
Single-Byte Character Set
Each character of a SBCS is encoded in exactly one byte.
7-bit encoded ASCII and the
8-bit encoded pre-Unicode
Western, Greek, Cyrillic etc. character sets are Single-Byte Character
Sets.
Double-Byte Character Set
A cover term for pre-Unicode CJK character sets. Each character of
a DBCS is encoded in exactly two bytes. A DBCS is always encoded
along with a 7-bit Single-Byte Character
Set such as ASCII or a
variant thereof, which results in a mixed system of double-byte and
single-byte encoded characters.
94x94 Character Set
A DBCS whose characters are
arranged in a matrix of 94 rows and 94 columns and are identified
by their row-cell numbers (Japanese
kuten,
Chinese
qu1wei4).
kuten,
Chinese 
qu1wei4).