Semiotics provides a theoretical framework to study different systems of signification and patterns of meaning formation. It is mainly based on concepts adapted from linguistics.

As linguistics studies natural language, semiotics studies various sign systems. Structuralist linguistic studies originate from the work of Ferdinand de Saussure. This field of study can be traced down to the linguistic studies of contemporary philosophers like Noam Chomsky.

Some other writers that have contributed to Semiotic studies are Roland Barthes, Louis Hjelmslev and Umberto Eco.

The basic unit of linguistics is the SIGN (gösterge). But in the Semiotics of Architecture we define this basic concept as the CODE which is much more suitable for our purpose.

The linguistic SIGN is schematized as below:
   
        Sd              Signified (gösterilen)
        Sr               Signifier (gösteren) 


This unit is nothing else but the word or the concept of the written or spoken language, we call this the natural language. The upper side of the diagram here represents the nature as a homogeneous substance originally without the cultural classifications and categorizations of the human mind. The word TREE in written script or spoken sound defines and signifies an entity in the nature, namely the natural TREE that can take  endlessly various shapes. The concept of TREE refers to a TYPE which represents many different examples (TOKEN).

One of the basic assertions of the structuralist thinking is that without the natural language and the related concept formation we would not be able to differentiate anything in nature. The analogy in architecture is someone not trained as an architect looking at a building and has very little to say about it: S/he would probably call it beautiful or ugly or interesting and might not recognize anything else.

It is not necessary for architectural codes that they are understood by the users to function effectively. The users usually get aware of problems only in the absence of solutions (or never at all).

The CODE in architectural design is very different from the linguistic SIGN in its nature. We can schematize the architectural CODE as below:

    Sd                a coded problem
    Sr                a coded solution

            
The linguistic SIGN defines a communicative signification, a relationship of standing for, representing, recalling or referring,

the architectural CODE, on the other hand, basically defines a functional signification, a relationship of realizing, fulfilling or carrying out a TASK. It is usually in the form of a coded solution to a coded problem.

The main idea here is that architects usually work with coded solutions and their knowledge about the problems they have to deal with is mainly based on the CODES they use by habit or convention. This kind of knowledge is basically referred to as TACIT knowledge. A CODE may also be defined as the epistemological unit of architectural knowledge.

Imagine a first year architectural student who designs a very simple house. The main entrance door is not articulated but looks like another opening on the façade. The teacher tells that this door should at least have a canopy above to protect from rain and snow the visitor who is waiting outside. The problem and the solution here are defined together almost as an inseperable unit that i