Manual communication systems use articulation of the hands, gestures, body language and facial expressions in place of the voice to mediate a message between persons. Being expressed manually, they are, of course, received visually, and sometimes tactually (see tactile signing). Manual communication is employed in systems that are codes for spoken languages, (see Manually Coded English), and with natural languages, such as in sign languages.

Other, simpler forms of manual communication have also been developed. They are neither natural languages nor even a code that can fully render one. They communicate with a very limited set of signals about an even smaller set of topics and have been developed for situations where speech is not practical or permitted, such as in cloistered religious communities, while underwater using scuba equipment, in television recording studios, in loud workplaces, while hunting (see Kalahari bushmen) or in the game Charades.