Short answers, pulled from the story.
Formal greetings typically involve a verbal acknowledgment and a handshake, while informal ones may rely on more relaxed gestures, casual words like "hi" or "hey", or a quick wave. Greeting customs also shift within a culture depending on social status and the relationship between the people involved.
The Gongshou is the most common Chinese greeting gesture, in which the right fist is placed in the palm of the left hand and both are shaken back and forth two or three times. It may be accompanied by a head nod or bow, and can be used when meeting, parting, congratulating, thanking, or apologizing.
Hat-tipping as a greeting declined in the mid-20th century when men largely stopped wearing hats outdoors. The gesture had been common from the Middle Ages onward, involving touching, slightly raising, or fully removing a hat to acknowledge someone, and carried connotations of social hierarchy.
The word "hey" has the oldest recorded citation as an English greeting, traced back to 1225 in the Oxford English Dictionary, where it is defined as a call to attract attention or an exclamation of exultation or surprise. "Hi", by contrast, became popular only in the 1920s.
Akazehe is a complex interlocking vocal rhythm that familiar women in rural Burundi use to greet each other. It is performed regardless of the contextual occasion or time of day.
Two kisses are most common throughout France as a whole. However, in Provence three kisses are given, in Nantes four are exchanged, and in Finistere at the western tip of Brittany and in Deux-Sevres in the Poitou-Charentes region, one kiss is preferred.