It is… possible to conceive of a science which studies the role of signs as part of social life. It would form part of social psychology, and hence of general psychology. We shall call it semiology (from the Greek semeîon, ‘sign’). It would investigate the nature of signs and the laws governing them. Since it does not yet exist, one cannot say for certain that it will exist. But it has a right to exist, a place ready for it in advance. Linguistics is only one branch of this general science. The laws which semiology will discover will be laws applicable in linguistics, and linguistics will thus be assigned to a clearly defined place in the field of human knowledge.
Ferdinand de Saussurre
‘semiotics is concerned with everything that can be taken as a sign’
Umberto Eco
‘Nothing is a sign unless it is interpreted as a sign.’
Charles Sanders Peirce