Greeting
Greeting is an act of communication in which people intentionally make their presence known to one another, showing attention and signalling a relationship that is usually cordial[^c1]. Greetings exist in all known human cultures[^c2], though their customs are highly culture- and situation-specific: a greeting may be spoken, gestural, written, or a combination of these, and the same word or gesture may serve both for meeting and for parting.
The best-known English greetings are surprisingly recent. "Hello" is first attested in writing from 1826[^c3], and its monosyllabic rival "hi" became popular only in the 1920s[^c4]. Gestural greetings are far older: the Western handshake can be traced to Greece in the 5th century BC, where it served as a gesture of peace showing that the hand held no weapon[^c5], while bows, curtsies, palm-together salutes, and nose-presses developed in cultures around the world. The modern telephone greeting emerged from a nineteenth-century contest of words, settled when Edison proposed "Hello" in a letter of 15 August 1877[^c6].
Greetings are studied as a form of phatic communion — communication which primarily serves to establish or maintain social relationships[^c7] — and they are governed by etiquette, which fixes what counts as polite, familiar, or rude in a given setting. Their history is one of recurring controversy: over the vulgarity of "hello", over the informality of "hi" in email, over the persistence of a false etymology linking the word to Bell's supposed fiancée, and over whether contact greetings should survive in an era of epidemic disease.
Greetings are also applied in practice — in email salutations, cross-cultural and professional encounters, language teaching, and public ritual — and they carry symbolic weight, as in World Hello Day, observed every 21 November to express that conflicts should be resolved through communication rather than the use of force[^c8]. The topic is not confined to human society: ethologists study ritualised greeting exchanges in other animals, which serve chiefly to maintain social bonds and cooperation rather than to defuse aggression after conflict[^c9][^c10], a body of work surveyed under [[Animal Greeting Behaviour]].