Greeting is a kind of communication behavior, in which human beings consciously inform each other of the existence of each other, so as to attract attention and suggest a kind of relationship (usually cordial) or social status (formal or informal) contact between the coming individuals or groups. Sometimes, greeting is just greeting before a conversation or when passing, for example on a sidewalk or footpath. Greeting customs are highly culture and situation specific and can change in a culture based on social status and relationships, but they exist in all known human cultures. Greetings can be heard or expressed physically, and are often a combination of the two. The subject does not include military etiquette, but includes etiquette other than gestures. Greetings or salutations can also be expressed in written communication, such as letters and e-mails.

Some times and cultures have very complex greeting rituals, such as greeting a monarch. On the contrary, secret societies often have furtive gestures and rituals, such as secret handshakes, to make members know each other.

In some languages and cultures, the same word or gesture is used as both a greeting and a farewell. For example, "good day" in English, "sat Shri akaal" in Punjabi, "as salamoualaikum" in Arabic, "Aloha" in Hawaiian, "Shalom" in Hebrew, "Namaste" in Hindi and "ciao" in Italian. Bows and handshakes are also used to greet and ask for leave.