Swiss linguist Ferdinand de Saussure was one of the key figures in the creation and study of semiotics. In his book "Course in General Linguistics," Saussure named the area of study "semiology" from the Greek word for "sign." His contemporary, Charles Sanders Peirce, is not as widely know, but also contributed early ideas to the formation of semiotics. Later, Roland Barthes and Umberto Eco, among others, continued the early work in the field while spreading it further into the areas of cultural studies.
There are two main threads of semiotics, the dyadic and the tryadic. The former, proposed by Saussure, argues the sign is made up of two elements--the "signifier" and the "signified." The latter, based on Peirce's work, claims there are three components--the representamen, the object and the interpretant.
With a dyadic sign, the signifier is the word or gesture that represents the signified. For example, the combination of letters r-o-c-k, the word "rock," and pointing at a rock all serve as signifiers for the actual rock itself (the signified).
With a tryadic sign, the representamen is that word or gesture that "represents" the actual item (Saussure's signifier), the object (the signified), and the interpretant, which claims that additional meaning making takes place on behalf of the person receiving the information (hearing the word, seeing the gesture). As such, the interpretant creates an additional sign in order to understand the initial sign.
Semiotics is further broken down into three areas: Semantics, Syntactics, and Pragmatics. Semantics looks specifically at the ways signs connect with those things to which they refer. Syntactics looks at the interactions of societal structures and the signs created within those structures. Pragmatics explores the way signs influence and affect the people who use and receive them.
Semiotics is a significant part of many socially oriented areas of study including anthropology, communication, sociology and cultural studies. It is used to analyze texts as well as verbal communications.