Manual communication systems use articulation of the hands (hand signs, gestures, etc.) to mediate a message between persons. Being expressed manually, they are received visually and sometimes tactually. When it is the primary form of communication, it may be enhanced by body language and facial expressions.
Manual communication is employed in sign languages and manually coded languages, though sign languages also possess non-manual elements. Other systems of manual communication have been developed for specific purposes, typically in situations where speech is not practical (such as loud environments) or permitted, or where secrecy is desired.