There are about 70 million deaf people who use sign language as their first language or mother tongue. It is also the first language and mother tongue to many hearing people and some deafblind people (tactile sign languages). Each country has one or sometimes two or more sign languages, although different sign languages can share the same linguistic roots in the same way as spoken languages do.

Sign language is not pantomime or a simple gestural code representing the surrounding spoken language. It is not an international language, but there are universal features in sign languages. This helps to make it possible for users of different sign languages to understand one another far more quickly than users of unrelated spoken languages can. This is has been called International Sign.

Sign language research started in the beginning of the 1960’s in the United States and the Netherlands. Nowadays research is done in many different universities all over the world. Linguistic research has confirmed that sign languages are complex natural languages and part of the Deaf culture at all levels from local to national.

Linguistic work has shown that natural signed languages show all the structural properties of other human languages and that they have evolved independently of the spoken languages which surround them. The visual-gestural-(tactual) (sign) medium is biologically normal and universal. Probably every known group of non-speaking deaf people observed around the world uses some sign language, and even isolated deaf individuals have been observed to develop a sign language to communicate with hearing relatives and friends.

Sign languages have supposedly existed as long as spoken languages. No one has invented them but they have arisen spontaneously through time by unrestricted interactions among people who use them as a primary communication system. They differ from devised or derivative sign languages that have been intentionally invented by some particular individuals (e.g., educators of deaf children) to represent spoken language. For example, ‘Manually Coded English’, ‘Signing Exact English’, ‘Linguistics of Visual English‘ are these kinds of systems. They are used in classrooms and do not spontaneously spread to a wider community or to broader employment in everyday communication.

Difference between sign and spoken languages is in different modalities they use. Signed languages are visual-gestural languages, while spoken languages are auditory-vocal languages. Forms of sign languages consist of sequences of movements and configurations of the hands and arms, face, and upper torso. The forms of spoken languages consist of sounds produced by sequences of movements and configurations of the mouth and vocal tract.

As spoken languages sign languages have a structure that can be further analysed and divided into smaller segments: sentences, signs and even smaller units. Sign languages are used according to grammars that can be described with the help of rules.

The use of sign and spoken languages doesn’t differ. Both can be used to provide and share information, tell true stories or lies, express poems, tell jokes, discuss scientific and abstract matters as well as have a speech or a lecture. A person giving the lecture uses sign language in a different way than is s/he is discussing with a good friend in an informal situation. One uses sign language differently to a small child than to an adult. Also dialects exist in sign languages. New signs develop all the time the same way as in spoken languages new words appear.

In every effort to improve deaf people’s human rights, the removal of linguistic barriers is of paramount importance. A deaf person must have the right to use sign language in any given situation.

Sign language should be recognized as the first language of a deaf child. The sign language used with the child must be the national sign language, i. e. the language of the adult Deaf community of that specific country. It is important that deaf children have early exposure to sign language and have the right to be educated as bilinguals or multilinguals regarding reading and writing because sign language is the only language that a deaf child can acquire without someone specifically teaching it.

Deaf children learn to use sign language from their environment as hearing children learn spoken languages from their parents and others.

The status of sign language varies in each country, therefore, the legislators and governments understand the roles of sign languages in different ways. In some countries the rights of Deaf people to education and equal participation in the society are secured by legislation. In others it is forbidden to use sign language even in class rooms. A deaf person’s access to sign language and belonging to a Deaf community should not be denied or ignored by governments. The first country in the world where sign language was recognized and passed into parliament was Uganda in 1995.

The development of any language, signed or spoken, and the culture where the language is practiced always is mutually influenced. No culture can emerge without language and no language can emerge without culture. In short, language and culture are closely related. However, cultures have a powerful influence on the development of language, both spoken and signed. Several countries sharing the same language can have different cultures, i.e. industrialized versus developing. The vocabulary of any language, both spoken and signed, in every country always is influenced by social, industrial, technological and other changes, known as cultural changes. Signed languages in different countries speaking a single language cannot be forced to become a single language.

Any forcible purification or unification of sign languages, conducted by governments, professionals working with Deaf people, and organizations for or of the Deaf, is a violation of the UN and UNESCO treaties, declarations and other policies, including the UN Convention on the Rights of Persons with Disabilities. Deaf people in every country have the sole right to make changes, if necessary, in their own local, provincial and national sign languages in response to cultural changes. The control of the development of any Sign Language must be left to any social group where the particular sign language is exercised.