ASL (American Sign Language) and BSL (British Sign Language) are both forms of manual communication used by deaf people. BSL and ASL are different languages, with different vocabularies and grammar structures.
Many deaf children born in the UK will start learning BSL from their parents at home. Some deaf children born in the US will also learn ASL, either from their parents or from other signers they meet. However, many deaf children in the US do not learn ASL and instead rely on spoken English and/or signed English (a manually coded form of English).
It can be difficult for parents to tell if their deaf child is using the correct form of sign language, as there is no one “correct”