Semiotics, also called semiology, the study of signs and sign-using behaviour. It was defined by one of its founders, the Swiss linguist Ferdinand de Saussure, as the study of “the life of signs within society.” Although the word was used in this sense in the 17th century by the English philosopher John Locke, the idea of semiotics as an interdisciplinary mode for examining phenomena in different fields emerged only in the late 19th and early 20th centuries with the independent work of Saussure and of the American philosopher Charles Sanders Peirce.
Three main types:
(1) An icon, which resembles its referent (such as a road sign for falling rocks)
(2) An index, which is associated with its referent (as smoke is a sign of fire)
(3) A symbol, which is related to its referent only by convention (as with words or traffic signals).
One such basic semiotic concept is Saussure’s distinction between the two inseparable components of a sign: the signifier, which in language is a set of speech sounds or marks on a page, and the signified, which is the concept or idea behind the sign.