Linguistics
ASL is a natural language, as proven to the satisfaction of the linguistic community by William Stokoe, and contains phonology, morphology, semantics, syntax and pragmatics just like oral languages. Like other sign languages, it is a manual language and a visual language: information is encoded not in sounds but with the shape and movement of the hands and other parts of the body, and with facial expressions, including mouthing. Sign languages are commonly misunderstood as being gestural, but while gesture is used in sign languages just as it is in oral languages (and indeed home sign is largely gestural), a sign language is fundamentally different from gesture in what it conveys and how it conveys it.
Read more about this topic: American Sign Language