It is possible to express oneself in sign language just as diversely as it is in any other language. The languages have regional variation, and different registers - from a formal register to the babble of children - just like spoken languages have. Structurally the signed languages are similar to each other. That is why it is easier for users of different sign languages to cross language borders than it is for people using spoken languages. Similarities in the way of life and the shared experience of living as deaf people among hearing people connect sign language users across national borders.
There is also something known as international sign. It is used for example at international events of the Deaf. It is, however, not a language in itself. It is a form of communication that varies from situation to situation, depending on the linguistic backgrounds of the users. It makes use of the similar structures of the signed languages and also partly on a small number of signs that have been agreed upon by the users in advance.
Sign language users can be deaf, hard of hearing, or hearing. Some learn the language at home from their Deaf parents. The majority of deaf children are however born to hearing parents and thus their first contact with sign language is outside the family. People using hearing aids or cochlear implants can also be sign language users. When referring to hearing children of Deaf parents the term CODA - or coda - (Child of Deaf Adult) is often used.