CODE

在通訊和資訊處理中，代碼（code）是指一套轉換資訊的規則系統，例如將一個字母、單詞、聲音、圖像或手勢轉換為另一種形式或表達，有時還會縮短或加密以便通過某種信道或儲存媒體通訊。一個最早的例子是語言的發明，它使人可以通過說話將他看到、聽到、感受到或想到的事情表達給其他人。但是，說話的通訊範圍局限於聲音可以有效傳播、辨識的範圍，並且發言只能傳達給現有的聽眾。將言談轉化為視覺符號的寫作擴大了跨越時間、空間的通訊表達。代碼有時亦稱代號等。

而編碼（encoding）能將源頭的資訊轉化為便於通訊或儲存的符號。解碼（Decoding）則是將其逆向還原的過程，將代碼符號轉化回收件人可以理解的形式。

編碼的其中一個原因是在平實語言、口語或寫作難以實現實現的情況下進行通訊。例如，旗語可以用特定標記表達特定資訊，站在遠處的另一個人可以解讀標識來重現該資訊。

In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form or representation, sometimes shortened or secret, for communication through a communication channel or storage in a storage medium. An early example is the invention of language, which enabled a person, through speech, to communicate what he or she saw, heard, felt, or thought to others. But speech limits the range of communication to the distance a voice can carry, and limits the audience to those present when the speech is uttered. The invention of writing, which converted spoken language into visual symbols, extended the range of communication across space and time.

The process of encoding converts information from a source into symbols for communication or storage. Decoding is the reverse process, converting code symbols back into a form that the recipient understand, such as English or Spanish.

One reason for coding is to enable communication in places where ordinary plain language, spoken or written, is difficult or impossible. For example, semaphore, where the configuration of flags held by a signaler or the arms of a semaphore tower encodes parts of the message, typically individual letters and numbers. Another person standing a great distance away can interpret the flags and reproduce the words sent.