Greetings, like common expressions, can be a small element that conveys a great depth of worldbuilding. Something as simple as the way two people say hello is an opportunity to expand your world. Greetings can convey what your people believe is important, they can be used to highlight formal or informal occasions, and they can be used to demonstrate membership to a specific group. Consider the following examples:

Attention Calls

Hello, Oy, Hi, Yo, Hey

These may be derived from old shouts, such as those used to hail ferrymen to the shore and let them know a passenger awaits.

Well Wishes

Commonly people will greet one another with a simple phrase wishing them peace, prosperity, and/or long life.

Praise/Condemnation

Greetings may come in the form of praise for a common deity, leader, or country. Or conversely may condemn such a thing (death to…)

Non-Verbal Gestures

Bows, handshakes, tipping a hat, and nods are all real-world gestures used as greetings. Consider if your world uses one of these or something similar. Gestures could be representative of some important element in your world. If your world contains alien or fantasy creatures, the gestures they use will depend on their own unique physiology.

Certain groups may have special greetings used to identify themselves or set themselves apart from others. Some of these greetings may be secret. A cult may have a secret handshake, a thief may tap their nose at a fence if they have wares to sell, or group of religious devotees may have a specific greeting for those on a pilgrimage.

Consider if there are differences in the ways greetings are expressed in formal or informal situations. Generally, formal greetings are more elaborate, especially if the greetings is occurring between a people of different social standings such as a knight and their king.