Communication oriented non-verbal sign system. Specifically this deals with non-verbal communication systems that are developed spontaneously among deaf people. These kind of sign languages are full and natural languages with their own universals. There is no single one sign language for all deaf people: every community of deaf people develops its own dialect. Sign languages are essentially different from spoken languages. Apart from the most obvious, the most important differences are: the simultaneity of the sign language (various signs can be shown simultaneously), the iconography of the sign (the origin of the sign lies in the relation between sign and referent), the necessity of direct eye contact (one needs to see the sign), and the greater role of context and situation for lack of functional words. The spontaneous development of sign language among deaf children is an indication of the innate predisposition to language acquisition of the human being.