1 bit
1 byte = 8 bits , in C language , called character or CHAR
=> can break a byte into two groups , one is called nibble , nnnn nnnn => 2 nibble.
1 word = 2 bytes = 16 bits , in C language , called an Integer , unsign 0~65535
=> MySQL smallint(5)
1 long word = 2 words = 4 bytes = 32 bits , unsign 0 ~ 4,294,967,295
=> MySQL int(10)