G'day is a colloquial Australian greeting. It is derived from the Irish language phrase "Gadheh," which translates literally as "God be with you."

G'day is a popular form of conversation used in Australia and New Zealand, and is used as both a greeting and a goodbye. It is also used extensively in other English-speaking countries.

G'day is a method of expressing friendliness and warmth to someone, either when meeting them or saying goodbye. It is an informal phrase, full of character and personality that conveys an easy-going mood.