This is the anniversary of a guru’s birth or death; marked by the holding of a festival. A gurpurb in Sikh tradition is a celebration of an anniversary related to the lives of the Sikh gurus. Observance of these anniversaries is an important feature of the Sikh way of life.
There are indications in the old chronicles that the gurus who succeeded Guru Nanak celebrated his birthday. Such importance was attached to the anniversaries that dates of the deaths of the first four gurus were recorded on a leaf in the first recension of the Scripture prepared by the Fifth Guru, Guru Arjan. The term gurpurb first appeared in the time of the gurus. It is a compound of the word purb (or parva in Sanskrit), meaning a festival or celebration, with the word guru. It occurs in at least five places in the writings of Bhai Gurdas (1551–1636), written in the time of Guru Arjan.
The three most celebrated gurpurbs are for Guru Nanak Dev Ji, Guru Arjun Dev Ji and Guru Gobind Singh Ji.