The full description from Wikipedia http://en.wikipedia.org/wiki/Semiotics
A partial description here:
Semiotics, semiotic studies, or semiology is the study of sign processes (semiosis), or signification and communication, signs and symbols, both individually and grouped into sign systems. It includes the study of how meaning is constructed and understood. One of the attempts to formalize the field was most notably led by the Vienna Circle and presented in their International Encyclopedia of Unified Science, in which the authors agreed on breaking out the field, which they called "semiotic", into three branches:
Semantics: Relation between signs and the things they refer to, their denotata.
Syntactics: Relation of signs to each other in formal structures.
Pragmatics: Relation of signs to their impacts on those who use them. (Also known as General Semantics)
These branches are clearly inspired by Charles W. Morris, especially his Writings on the general theory of signs (The Hague, The Netherlands, Mouton, 1971, orig. 1938).
Semiotics is frequently seen as having important anthropological dimensions, for example Umberto Eco proposes that every cultural phenomenon can be studied as communication. However, some semioticians focus on the logical dimensions of the science. They examine areas belonging also to the natural sciences - such as how organisms make predictions about, and adapt to, their semiotic niche in the world (see semiosis). In general, semiotic theories take signs or sign systems as their object of study: the communication of information in living organisms is covered in biosemiotics or zoosemiosis.