According to DIN 43000, a code is a rule for the unambiguous assignment of characters of one character set to those of another character set. For the assignment of the characters of one character set to those of another, one uses such character sets with which the best representation can be achieved.
The code with the smallest possible character set is the binary code with the two characters "0" and "1". For synchronous data transmission, the ASCII character set and the EBCDIC code are most frequently used.
Codes can be classified according to certain characteristics such as the structure and are used in all technical disciplines. In merchandise management with the bar codes and the 2D codes, in monetary transactions with the Bank Identifier Code( BIC) or the International Bank Account Number( IBAN) , in data transmission with the various codes for signal adaptation and transfer optimization or in radio technologies with the convolutional codes and the many modulation codes for identifying the modulation techniques.