Title: Nod (gesture)
Content:  There are several exceptions: in Greece, Cyprus, Iran, Turkey, Bulgaria, Albania, and Sicily a single nod of the head up (not down) indicates a "no". Some cultures also swap the meanings between nodding and head shaking. Specifically in Greece and in Cyprus, the single nod of the head up that indicates "no" is almost always combined with a simultaneous raise of the eyebrows and most commonly also with a slight (or complete) rolling up of the eyes. There is also a sound that sometimes accompanies the whole gesture, called "τσου". This sound bears heavy resemblance, but is not identical, to the British tutting sound. The use of "τσου" is optional and reserved only for heavy emphasis on the "no". The emphasis on the raised eyebrows and the rolling up of the eyes is such, that the actual nod of the head upwards has ended up being of secondary importance. A person can denote "no" by simply raising their eyebrows and rolling up their eyes, with the head staying completely still.
Title: Nod (gesture)
Content:  A nod of the head is a gesture in which the head is tilted in alternating up and down arcs along the sagittal plane. In many cultures, it is most commonly, but not universally, used to indicate agreement, acceptance, or acknowledgement.
Title: Body language
Content:  Germany. But this same gesture is insulting in other countries like Iran, Bangladesh and Thailand, where it is the equivalent of showing the middle finger in the US. In most cultures the Head Nod is used to signify 'Yes' or agreement. It's a stunted form of bowing – the person symbolically goes to bow but stops short, resulting in a nod. Bowing is a submissive gesture so the Head Nod shows we are going along with the other person's point of view. Research conducted with people who were born deafblind shows that they also use this gesture to signify 'Yes'.
Title: Nod (gesture)
Content:  Nodding can also be used as a form of nonverbal greeting or acknowledgement of another's presence; in this context, it is essentially an especially mild form of bowing, with just enough movement to show a degree of respect without additional formality. This includes the traditional downwards nod, or the upwards nod (which is more informal and usually used among friends or subordinates). To increase the formality, the downwards nod may also be accompanied by a suitable verbal greeting.
Title: Nod (gesture)
Content:  Different cultures assign different meanings to the gesture. Nodding to indicate "yes" is widespread, and appears in a large number of diverse cultural and linguistic groups. Areas in which nodding generally takes this meaning include the Indian subcontinent (note that the head bobble also shows agreement there), the Middle East, Southeast Asia, most of Europe (see below), South America and North America. Nodding may also be used as a sign of recognition in some areas, or to show respect. An insult may be inferred if it is not returned in kind. In Greece, the single nod of the head down that indicates "yes" is often combined with closing the eyes simultaneously. This nod commonly also includes a very slight, almost unnoticeable, turn of the head to 
Title: Body language
Content:  there is a relationship between prolonged poor posture of the head and neck, and negative mental states. As such, body language which involves the head and neck should not cause strain and seek to be as natural as possible. As with all forms of body language, it is useful to understand as many other connected factors as possible in order to accurately identify the meaning. Nodding of the head is generally considered as a sign of saying 'yes'. When used in conversation it may be interpreted as a sign of approval and encourage the speaker to go on. A single nod of the head is a sign 
Title: Gesture
Content:  point at something to indicate that you want to show a person something to indicating a thumbs up to show everything is good. Some gestures are near universals, i.e., found all over the world with only some exceptions. An example is the head shake to signify "no". Also, in most cultures nodding your head signifies "Yes", which the book "The Definitive Book of Body Language" describes as submissive gesture to representing the conversation is going the direction of the person speaking. The book explains that people who are born deaf can show a form of submissive gesture to signify "Yes".
Title: Body language
Content:  acknowledging another person in a respectful manner; in this manner it is similar to the Asian practice of bowing to a person as a sign of respect. Shaking the head is usually interpreted as meaning 'no'. In terms of meaning, it is the opposite of nodding. In India, a head bobble is the tilting of the head from side to side and is a common sign of saying yes, ok, or I understand in some manner. Its interpretation can be ambiguous and depends very much on the context in which it is applied. When a lowering of the head is emphasised in conjunction with the eyes then 
Title: Nonverbal communication
Content:  North American way of applauding, but in Spain is used to summon a waiter at a restaurant. Differences in nodding and shaking the head to indicate agreement and disagreement also exist. Northern Europeans nodding their heads up and down to say "yes", and shaking their head from side to side to say "no". But the Greeks have for at least three thousand years used the upward nod for disagreement and the downward nod for agreement." There are many ways of waving goodbye: Americans face the palm outward and move the hand side to side, Italians face the palm inward 
Title: Head shake
Content:  However, in some Southeastern European areas such as Bulgaria and southern Albania, it is used for the opposite purpose, to indicate affirmation, meaning "yes". In those regions, nodding in fact means "no" as well, the complete reverse of most other places in the world.

Question: nodding your head no is an example of?
Answer: a gesture.