A
sign system is a key concept in
semiotics and is used to refer to any system of
signs and relations between signs. The term
language is frequently used as a synonym for a sign-system. However, the term
sign-system is preferable to the term
language for a number of reasons. First, the use of the term
language tends to carry with it
connotations of human language, particularly human spoken language. Human spoken language is only one example of a sign-system; albeit probably one of the most complex sign-systems known. For example, in traditional forms of face-to-face communication, humans communicate through
non-verbal as well as verbal sign-systems; colloquially, this can be referred to as
body language. Hence, humans communicate a great deal by way of facial movements and other forms of bodily expression. Such expressions are also signs and an organised collection of such signs would be considered a sign system. Second, the same concept of a sign-system can be used in considering a vast range of communication forms such as
animal communication and
man-machine communication. Examination of simpler forms of such systems of signs within non-human communication can help to illuminate some of the essence of
communication and in particular can help to provide tentative answers to the question of the nature and function of communication.