One easy determination is age. If someone is older than you, then you should wai them unless they are someone whom you employ, such as a housekeeper. Additionally, you should never wai to anyone who you are paying for service, such as waiters, tailors, vendors, shopkeepers or taxi drivers. You also wouldn't wai your peers and friends. Alternatively, when leaving a party or other such gathering, you should wai everyone, as this is the polite way to excuse yourself from the festivities