Words have limitations. There are numerous areas where nonverbal communication is more effective than verbal (describing the shape of something, or providing quick direction, for instance). We can't control nonverbal behaviors as easily as spoken words. Since nonverbal communication may be unconscious, it tends to be more genuine than words. Nonverbal signals can express feelings inappropriate to state: social etiquette limits what can be said, but nonverbal cues can communicate thoughts. A separate communication channel is useful to help send complex messages: a speaker can add enormously to the complexity of the verbal message through simple nonverbal signals."  (Jones)