The notion of linguistic sign was introduced by Ferdinand de Saussure. By linguistic signs, we mean the entities used in natural languages, such as morphs, lexemes, and phrases.
Linguistic signs have several specific properties, the most obvious of which is that they are to be combined together into larger signs and each one can in turn consist of several smaller signs. Natural language can be viewed as a system of linguistic signs.
As another property of linguistic sign, its signifier at the surface level consists of elementary parts, phonetic symbols in the phonetic transcription or letters in the written form of language. These parts do not have any signified of their own: a letter has no meaning, but certain strings of letters do have it.
We have already mentioned other notation systems to represent words of natural language, such as hieroglyphic writing. Each hieroglyph usually has its own meaning, so a hieroglyph is a linguistic sign. The gestures in the sign language for deaf people in some cases do have there own meanings, like hieroglyphs, and in other cases do not have any meaning of their own and serve like letters.