It is found that there is never really figured out these concepts. I checked MSDN today and I finished it.
Char:
The char value type represents a Unicode character, also known as the Unicode code point, is implemented as a 16-bit digital value, which ranges from hexadecimal value 0x0000 to 0xFFFF. String (Collection of Char objects). As a general principle, the .NET Framework uses or returns a class member of char to operate the CHAR's digital (serial number) value. The semantic value of the string is performed using or returns a String class member, including processing a proxy item pair. For this reason, Char does not have to equivore individual characters in String.
BYTE:
The BYTE value type indicates an unsigned integer between 0 and 255. (8-bit)
Bit:
Bit (bits) is a digit of digital technology binary. 1 bit binary is called 1bit, which consists of two yards, namely 0 and 1, represents two states of the line. One byte (byte) is constituted every 8bit, ie 8bit = 1byte. Binary code transfer rate is called bit rate (BPS or B / S)
