Sign language is the natural language of deaf people. Through it they can relate to their social environment because it allows them to establish a basic communication channel that is visual and spatial.
It should be clarified that sign language is not simple mimicry and neither is it a visual reproduction of some simplified version of oral language. It has a rich and distinctive grammatical structure, characterized by the configuration of the hands, their movements, their orientations, their spatial location and non-manual elements, such as lip, facial, and lingual movements, etc. Like any other language, it can be used to discuss any topic, be it simple and concrete or dense and abstract. Furthermore, like oral language, it is organized into meaningless elementary units.
It is important to clarify that the LSE does not consist of a simple mimicry or a visual reproduction of oral language. The Spanish sign language is a legally recognized language in the Spanish state (Law 27/2007, of October 23, which recognizes the Spanish sign languages and regulates the means of support for oral communication of deaf people, with hearing disabilities and deafblind) that has a rich grammatical structure and that, like any other language, can be used to discuss any topic, be it simple and concrete or dense and abstract.
Furthermore, like oral language, it is organized by elementary units with meaning and without meaning; that is, instead of words, we use signs (units with meaning) and instead of phonemes, we use queremas that are grouped into parameters (units without meaning). To better understand this, we can read the entry "Formative parameters of the sign".
In the educational field, especially in special education, it is very common to use signs as a support for oral language.
The child does not necessarily have to be deaf to be able to use them, but any child who has a hearing loss or articulatory difficulties, who only utters a few words, or directly who does not have an oral language but if he hears perfectly, as may be the case with many children with autism, can and should learn and use them as the purpose of supporting their communication, in order to express themselves and be understood.
There are many sign languages around the world, due to the appearances and independent evolutions of each one of them. In fact, some countries have more than one sign language, such as Spain (Spanish sign language and Catalan sign language).
What does exist is an International Signaling System (ISS) invented from the lexicon and rules of operation of different sign languages, but its use is reduced to very specific occasions, such as International Congresses, and it is not a language but a artificial system.
