A Hongi is a Maori Traditional greeting in which people press their nose & forehead together. It is used in traditional meetings among Moari people and on major ceremonies and serves a similar purpose to a formal handshake in a modern western culture. In the Hongi the "HA" or breath of life is to exchange. The breath of life can also be interpreted as sharing both party souls.
Through the exchange of this phsical greeting, one is no longer a visitor but they are called on of the people of the Land. For the remainder of one's stay one is obliged to share in all the duties and responsibilites of the home people.
That is little information about the Hongi!