Semantics

Semantics refers to the meaning of a construct, as opposed to its syntax - the pattern of constituent elements in the construct. The term is most often used with programming language source code, where the semantics of the program refers to what the program and its constituent parts actually do when the program is executed. However, the term is used of many things in computers; e.g. the header of an email message includes elements with semantic import, as they control what will happen to the message when it is sent..