Encoding

The word encoding has a number of meanings:

Character encoding is a code that pairs a set of natural language characters (such as an alphabet or syllabary) with a set of something else, such as numbers or electrical pulses.
Text encoding uses a markup language to tag the structure and other features of a text to facilitate processing by computers. (See also Text Encoding Initiative.)
Semantics encoding of formal language A in formal language B is a method of representing all terms (e.g. programs or descriptions) of language A using language B.
Encoding transforms a signal into a form optimized for transmission or storage, generally done with a codec.

The term encoding is often used to refer to encryption, but the term "encoding" implies no use of a key.