Another use of codes is cryptography, whereby a codebook is used to control semantic substitution, preventing those without a codebook from understanding the transmission. This should be contrasted with 'cypher?' which also prevents understanding by replacing syntactic elelments (eg, letters) with something else. These are not codes.
Probably the most widely known code in use today is ASCII; it is more correctly referred to as a 'representational assignment list'. Secrecy is not an intent in ASCII, and if it were, ASCII would be a cypher in any case. It is employed by nearly all personal computers, terminal?s, printers, and other communication equipment. It represents 128 characters with seven-bit binary numbers - i.e., as a string of seven 1s and 0s. In ASCII a lowercase "a" is always 1100001, an uppercase "A" always 1000001, and so on. Extensions to ASCII have included 8-bit characters (non-Latin letters and such things as card suit symbols), and in fullest flowering have included glyphs from essentially all of the world's writing systems - Unicode.
Acronyms and abbreviations can be considered codes, and in a sense all languages and writing systems are codes for human thoughts. Occasionally a code word achieves an independent existence (and meaning) while the original equivalent phrase is forgotten or at least no longer has the precise meaning attributed to the code word. For example, the number "86" was once used as a code word in restaurants meaning "We're out of the requested item". It is now commonly used to mean the removal or destruction of something.
The word code is also used to refer to the result of computer programming; this use of the word has not yet passed from jargon into general vocabulary, however. In this usage, "code" typically stands for "source code", and "to code" means "to write source code, to program". This usage is socially marked; identifies its user as an "insider" in computer programming.
The word is also used to refered to rules or laws such as in code of honor, municipal code, traffic code, dress code, penal code etc.
This word has acquired a large number of subtly and grossly incompatible meanings. Use with care.
see also morse code, country codes