Nonverbal communication is all communication without language. It's basically the miscellaneous category.
Nonverbal communication especially can be unintentional or intentional - unless you're Hazou or a social-spec, in which case it's always intentional. Remember how I mentioned the difference between intent? Yeah, that's coming back. Listeners tend to prioritize leakage cues - nonverbal messages that leak out without control - over the verbal message when the two clash, or even when they don't. Regardless, the "uncontrolled" nonverbal is valued more.
Nonverbal communication, however, is nearly always ambiguous, with multiple meanings since none are assigned.
Nonverbal communication has several functions:
Reinforcing verbal messages - e.g holding up a hand while saying "stop", smashing a fist into your hand while saying "they're going to pay", or holding up a finger and saying "first"/
Substituting for verbal messages - e.g. holding up a hand, throwing a punch, etc.
Contradicting verbal messages - e.g. rolling your eyes to emphasize sarcasm
Managing and regulating interactions - e.g holding up a hand to speak, walking away, etc.
Creating Immediacy - creating a feeling of closeness, involvement, warmth, etc. through proximity, smiling, etc.
Deceit - technically, people watch out for a bunch of cues (anxiety, avoiding eye contact, blinking frequently, awkward body movements) but most of those are not actually associated with lying anyway. Also, people IRL default to believing each other and especially the closer the relation is.
Etc.
Nonverbal communication has a couple of codes through which nonverbals are communicated.
Kinesics is the use of gestures and body languages. Synchronized body movements can increase cooperation and likeability. Kinesics have five broad internal categories:
Illustrators - visually explain verbal message
Regulators - regulate the flow of iteractions
Emblems - movements or gestures specific to groups or cultures that have a direct verbal translation
Adaptors - satisfy a physical or physiological need, and reduces tensions.
Affect display - movement that conveys emotion.
Facial expressions is the use of the face to express emotion. There's seven basic ones and about a billion more complicated ones, etc. etc. Emotional intelligence is buried in here in my notes for whatever reason, but Emotional intelligence is the ability to be aware of, identify, and manage personal emotions by regulating the intensity of those emotions (e.g. breathing exercises after bombing test).
Oculesics - use of eyes to communicate. How it does so varies from culture to culture - the most memorable incident from MfD being Noburi and Yuno walking down a street, F L I R T I N G. Avoidance is often taken as dishonesty, insincerity, or discomfort.
Functions:
Influencing attitude change
Indicating degree of arousal.
Expressing emotion.
Regulating interaction.
Indicating power.
Forming impressions.
Paralanguage - voice stuff around language. Includes stuff like pitch, tone, volume, voice quality, accents, rate, and rhythm of words. The most consistently popular speech qualities include smoothness, precision, and fluidity of speech. Also includes stuff like vocalizations - utterances that communicate emotional or physical state - and backchannel cues, which signal when to listen or speak further.
Physical appearance sends messages too. Artifacts especially can express a lot about a person. Note also that the association between physical appearances can change over time too - what was fashionable thirty years ago is...less so today.
Proxemics - use of space to communicate. Comfortable distances vary from culture to culture, but generally speaking, the farther away someone has to be to be comfortable talking to you, the more emotionally distant the two of you are. Violating personal space, or at least the comfortable distance for the relational distance, is always awkward and uncomfortable.
Territoriality - claiming an area through continuous occupation.
Environment - usually stuff like where you live. Communicates personality.
Haptics - use of touch to send messages. Adjusts based on situation and context. There's a range based on intimacy - see...
Functional-professional - e.g handshake
Social-polite - e.g thumbs-up, clapping
Friendship-warmth - e.g fistbump
Love-intimacy - e.g hug
Sexual-arousal - e.g literally guess. literally. fucking. guess.
Anyway, they're used to express emotion, control other people, or as a ritual.
Chronemics - use of time to send messages. this includse stuff like response rate and how often people spend time together. Spending time together communicates concern and interest; response rates communicate interest and immediacy. (e.g choosing to not spend time with a person signals disinterest, hanging out with a person all the time the exact opposite, etc.)
Cultures obviously play a big role in this - a famous one is the difference between contact and noncontact cultures, and how that affects comfortable distances.
Situational context also plays a big role, where the obvious dimensions are the public-private dimensions, and the informal-formal dimensions.