Learn in the textbookEncoding and Character Codes
DefinitionEncoding (符号化) means mapping information such as text, sound or images to codes such as bit strings according to fixed rules.
ExplanationIf sender and receiver share the mapping rules (the code system), the receiver can turn the code back into the original information, which is decoding; if the rules differ, the result can be garbled text and similar errors. A code of n bits can distinguish 2^n patterns, so the number of bits needed follows from how many kinds of things must be represented. Code length is either fixed-length, the same for every item, or variable-length, differing from item to item.
AnalogyIt is like assigning meanings in advance to a lighthouse's flashing patterns. Only ships holding the same table can read the meaning from the flashes.
Memory hookThe Japanese term 符号化 combines 符号 (a signal mark) and 化 (turning into); its reverse, 復号, uses 復 (restore): getting the original back from the code.