Guru Nanak is the first guru in the Sikh religion. In the Sikh religion we do not call the day of the birth of our Guru a birthday, instead we say parkash. Guru Nanak’s parkash took place on October 20th, 1469 A.D. in Rai Bhoi di Talwandi, (now known as Nankana Saheb) in the sheikhupura district of Pakistan. Guru Nanak came to this world during a time when this world was covered with the darkness of ignorance, tyranny, oppression, religious and cultural superstitions and sins. He came to save us from this Dark Age. 
  

siqgur nwnk pRgitAw imtI DuMD jg cwnx hoAw] 
ijauN kr sUrj inkilAw qwry Cpy AMDyr ploAw] 

Translation: 
  With the emergence of the true Guru Nanak, the mist cleared and the light scattered all around. As if at the sunrise the stars disappear and the darkness dispels.   

That is "With the appearance of Guru Nanak, the mist of ignorance disappeared and there was the light of righteousness”   Bhai Gurdas Ji tells us why Guru Nanak came to this world: 
  

suxI pukwr dwqwr pRB gur nwnk jg mwihM pTwXw] kil qwrx gur nwnk AwXw ] 

  Translation: 
  God listened to the cries (of humanity) and sent Guru Nanak to this world. 
Guru Nanak came to save us in this Dark Age. 

  Guru Nanak's father Mehta Kalu (mihqw kwlU) was a village official in charge of land records and revenue. He worked for Rai Bular (rwie bulwr), The ruler of that village. The Guru's mother's name was Mata (mother) Tripta (mwqw iqRpqw). Guru Nanak had one older sister whose name was Bibi Nanaki (bIbI nwnkI). Bibi Nanaki was 5 years older than guru Nanak and she was the first to recognize Guru Nanak as a guru. 
  Upon the birth of his son, Mehta Kalu called Hardial Brahmin (hridAwl), a Hindu priest to come and bless the child. Pundit Hardial immediately saw that this child was different. 

Pundit Hardial was the one who named Guru Nanak:   

puMin purohq nwm ibcwrn lwgw[nwnk nwm AnBY Anurwgw[ 
                                                                              (Mahima Prakash) 

Hardial told Mehta Kalu, “This child will be very important one day. He will be respected all around the world and he will help show the path to God. He will be the savior for both Hindus and Muslims alike.”                               

copeI ieh issu ko mwnihgy doaU]ihMdU qurk isK hoie sBkoaU] 
iesky crn poq kI inAweI]pwr prih pRmwrQ pweI ]51] 
sMgq krihM qrihM Bvswgr]skl jgq mih hoieM aujwgr] 
bhuq nrn ko krihM auDwrw]nwm Bgq dYdwn audwrw]52] 
                                                         (Sri Guru Nanak Parkash) 

Translation: 
Hindus and Muslims will both respect him and become his followers. 
His feet are like a boat, whoever follows his path; he will cross the ocean of life. 
He will save many people by giving them the name of God. 

  Today there is a Gurdwara (temple) named Junam Usthan (gurduAwrw jnm AsQwn ) built at the site where Guru Nanak’ parkash took place. His birthday is celebrated on the full moon night, which usually falls within the month of November.   From his early childhood, Guru Nanak was a priceless jewel, a shining star, and a divine light that shined out from among his peers. His wise questions and spiritual enlightenment surprised all those who came in contact with him.