<P> Hindus celebrate the birth anniversary day every year when the day that corresponds to lunar month or solar month (Sun Signs Nirayana System--Sourava Mana Masa) of birth and has the same asterism (Star / Nakshatra) as that of the date of birth . That age is reckoned whenever Janma Nakshatra of the same month passes . </P> <P> Hindus regard death to be more auspicious than birth since the person is liberated from the bondages of material society . Also, traditionally, rituals & prayers for the departed are observed on 5th and 11th day with many relatives gathering . </P> <P> Many monasteries celebrate the anniversary of Buddha's birth, usually in a highly formal, ritualized manner . They treat Buddha's statue as if it was Buddha himself, as if he were alive; bathing, and "feeding" him . </P> <P> Sikhs celebrate the anniversary of the birth of Guru Nanak . </P>

Where did the custom of celebrating birthdays come from